linux/drivers/infiniband/ulp/ipoib/ipoib_multicast.c

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/*
* Copyright (c) 2004, 2005 Topspin Communications. All rights reserved.
* Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
* Copyright (c) 2004 Voltaire, Inc. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/moduleparam.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/igmp.h>
#include <linux/inetdevice.h>
#include <linux/delay.h>
#include <linux/completion.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 16:04:11 +08:00
#include <linux/slab.h>
#include <net/dst.h>
#include "ipoib.h"
#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG
static int mcast_debug_level;
module_param(mcast_debug_level, int, 0644);
MODULE_PARM_DESC(mcast_debug_level,
"Enable multicast debug tracing if > 0");
#endif
struct ipoib_mcast_iter {
struct net_device *dev;
union ib_gid mgid;
unsigned long created;
unsigned int queuelen;
unsigned int complete;
unsigned int send_only;
};
/* join state that allows creating mcg with sendonly member request */
#define SENDONLY_FULLMEMBER_JOIN 8
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
/*
* This should be called with the priv->lock held
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
*/
static void __ipoib_mcast_schedule_join_thread(struct ipoib_dev_priv *priv,
struct ipoib_mcast *mcast,
bool delay)
{
if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
return;
/*
* We will be scheduling *something*, so cancel whatever is
* currently scheduled first
*/
cancel_delayed_work(&priv->mcast_task);
if (mcast && delay) {
/*
* We had a failure and want to schedule a retry later
*/
mcast->backoff *= 2;
if (mcast->backoff > IPOIB_MAX_BACKOFF_SECONDS)
mcast->backoff = IPOIB_MAX_BACKOFF_SECONDS;
mcast->delay_until = jiffies + (mcast->backoff * HZ);
/*
* Mark this mcast for its delay, but restart the
* task immediately. The join task will make sure to
* clear out all entries without delays, and then
* schedule itself to run again when the earliest
* delay expires
*/
queue_delayed_work(priv->wq, &priv->mcast_task, 0);
} else if (delay) {
/*
* Special case of retrying after a failure to
* allocate the broadcast multicast group, wait
* 1 second and try again
*/
queue_delayed_work(priv->wq, &priv->mcast_task, HZ);
} else
queue_delayed_work(priv->wq, &priv->mcast_task, 0);
}
static void ipoib_mcast_free(struct ipoib_mcast *mcast)
{
struct net_device *dev = mcast->dev;
int tx_dropped = 0;
ipoib_dbg_mcast(ipoib_priv(dev), "deleting multicast group %pI6\n",
mcast->mcmember.mgid.raw);
IPoIB: Use a private hash table for path lookup in xmit path Dave Miller <davem@davemloft.net> provided a detailed description of why the way IPoIB is using neighbours for its own ipoib_neigh struct is buggy: Any time an ipoib_neigh is changed, a sequence like the following is made: spin_lock_irqsave(&priv->lock, flags); /* * It's safe to call ipoib_put_ah() inside * priv->lock here, because we know that * path->ah will always hold one more reference, * so ipoib_put_ah() will never do more than * decrement the ref count. */ if (neigh->ah) ipoib_put_ah(neigh->ah); list_del(&neigh->list); ipoib_neigh_free(dev, neigh); spin_unlock_irqrestore(&priv->lock, flags); ipoib_path_lookup(skb, n, dev); This doesn't work, because you're leaving a stale pointer to the freed up ipoib_neigh in the special neigh->ha pointer cookie. Yes, it even fails with all the locking done to protect _changes_ to *ipoib_neigh(n), and with the code in ipoib_neigh_free() that NULLs out the pointer. The core issue is that read side calls to *to_ipoib_neigh(n) are not being synchronized at all, they are performed without any locking. So whether we hold the lock or not when making changes to *ipoib_neigh(n) you still can have threads see references to freed up ipoib_neigh objects. cpu 1 cpu 2 n = *ipoib_neigh() *ipoib_neigh() = NULL kfree(n) n->foo == OOPS [..] Perhaps the ipoib code can have a private path database it manages entirely itself, which holds all the necessary information and is looked up by some generic key which is available easily at transmit time and does not involve generic neighbour entries. See <http://marc.info/?l=linux-rdma&m=132812793105624&w=2> and <http://marc.info/?l=linux-rdma&w=2&r=1&s=allows+references+to+freed+memory&q=b> for the full discussion. This patch aims to solve the race conditions found in the IPoIB driver. The patch removes the connection between the core networking neighbour structure and the ipoib_neigh structure. In addition to avoiding the race described above, it allows us to handle SKBs carrying IP packets that don't have any associated neighbour. We add an ipoib_neigh hash table with N buckets where the key is the destination hardware address. The ipoib_neigh is fetched from the hash table and instead of the stashed location in the neighbour structure. The hash table uses both RCU and reference counting to guarantee that no ipoib_neigh instance is ever deleted while in use. Fetching the ipoib_neigh structure instance from the hash also makes the special code in ipoib_start_xmit that handles remote and local bonding failover redundant. Aged ipoib_neigh instances are deleted by a garbage collection task that runs every M seconds and deletes every ipoib_neigh instance that was idle for at least 2*M seconds. The deletion is safe since the ipoib_neigh instances are protected using RCU and reference count mechanisms. The number of buckets (N) and frequency of running the GC thread (M), are taken from the exported arb_tbl. Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com> Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Roland Dreier <roland@purestorage.com>
2012-07-25 01:05:22 +08:00
/* remove all neigh connected to this mcast */
ipoib_del_neighs_by_gid(dev, mcast->mcmember.mgid.raw);
if (mcast->ah)
ipoib_put_ah(mcast->ah);
while (!skb_queue_empty(&mcast->pkt_queue)) {
++tx_dropped;
dev_kfree_skb_any(skb_dequeue(&mcast->pkt_queue));
}
netif_tx_lock_bh(dev);
dev->stats.tx_dropped += tx_dropped;
netif_tx_unlock_bh(dev);
kfree(mcast);
}
static struct ipoib_mcast *ipoib_mcast_alloc(struct net_device *dev,
int can_sleep)
{
struct ipoib_mcast *mcast;
mcast = kzalloc(sizeof *mcast, can_sleep ? GFP_KERNEL : GFP_ATOMIC);
if (!mcast)
return NULL;
mcast->dev = dev;
mcast->created = jiffies;
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
mcast->delay_until = jiffies;
mcast->backoff = 1;
INIT_LIST_HEAD(&mcast->list);
INIT_LIST_HEAD(&mcast->neigh_list);
skb_queue_head_init(&mcast->pkt_queue);
return mcast;
}
static struct ipoib_mcast *__ipoib_mcast_find(struct net_device *dev, void *mgid)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
struct rb_node *n = priv->multicast_tree.rb_node;
while (n) {
struct ipoib_mcast *mcast;
int ret;
mcast = rb_entry(n, struct ipoib_mcast, rb_node);
ret = memcmp(mgid, mcast->mcmember.mgid.raw,
sizeof (union ib_gid));
if (ret < 0)
n = n->rb_left;
else if (ret > 0)
n = n->rb_right;
else
return mcast;
}
return NULL;
}
static int __ipoib_mcast_add(struct net_device *dev, struct ipoib_mcast *mcast)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
struct rb_node **n = &priv->multicast_tree.rb_node, *pn = NULL;
while (*n) {
struct ipoib_mcast *tmcast;
int ret;
pn = *n;
tmcast = rb_entry(pn, struct ipoib_mcast, rb_node);
ret = memcmp(mcast->mcmember.mgid.raw, tmcast->mcmember.mgid.raw,
sizeof (union ib_gid));
if (ret < 0)
n = &pn->rb_left;
else if (ret > 0)
n = &pn->rb_right;
else
return -EEXIST;
}
rb_link_node(&mcast->rb_node, pn, n);
rb_insert_color(&mcast->rb_node, &priv->multicast_tree);
return 0;
}
static int ipoib_mcast_join_finish(struct ipoib_mcast *mcast,
struct ib_sa_mcmember_rec *mcmember)
{
struct net_device *dev = mcast->dev;
struct ipoib_dev_priv *priv = ipoib_priv(dev);
struct rdma_netdev *rn = netdev_priv(dev);
struct ipoib_ah *ah;
struct rdma_ah_attr av;
int ret;
int set_qkey = 0;
mcast->mcmember = *mcmember;
/* Set the multicast MTU and cached Q_Key before we attach if it's
* the broadcast group.
*/
if (!memcmp(mcast->mcmember.mgid.raw, priv->dev->broadcast + 4,
sizeof (union ib_gid))) {
spin_lock_irq(&priv->lock);
if (!priv->broadcast) {
spin_unlock_irq(&priv->lock);
return -EAGAIN;
}
/*update priv member according to the new mcast*/
priv->broadcast->mcmember.qkey = mcmember->qkey;
priv->broadcast->mcmember.mtu = mcmember->mtu;
priv->broadcast->mcmember.traffic_class = mcmember->traffic_class;
priv->broadcast->mcmember.rate = mcmember->rate;
priv->broadcast->mcmember.sl = mcmember->sl;
priv->broadcast->mcmember.flow_label = mcmember->flow_label;
priv->broadcast->mcmember.hop_limit = mcmember->hop_limit;
/* assume if the admin and the mcast are the same both can be changed */
if (priv->mcast_mtu == priv->admin_mtu)
priv->admin_mtu =
priv->mcast_mtu =
IPOIB_UD_MTU(ib_mtu_enum_to_int(priv->broadcast->mcmember.mtu));
else
priv->mcast_mtu =
IPOIB_UD_MTU(ib_mtu_enum_to_int(priv->broadcast->mcmember.mtu));
priv->qkey = be32_to_cpu(priv->broadcast->mcmember.qkey);
spin_unlock_irq(&priv->lock);
priv->tx_wr.remote_qkey = priv->qkey;
set_qkey = 1;
}
if (!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)) {
if (test_and_set_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
ipoib_warn(priv, "multicast group %pI6 already attached\n",
mcast->mcmember.mgid.raw);
return 0;
}
ret = rn->attach_mcast(dev, priv->ca, &mcast->mcmember.mgid,
be16_to_cpu(mcast->mcmember.mlid),
set_qkey, priv->qkey);
if (ret < 0) {
ipoib_warn(priv, "couldn't attach QP to multicast group %pI6\n",
mcast->mcmember.mgid.raw);
clear_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags);
return ret;
}
}
memset(&av, 0, sizeof(av));
av.type = rdma_ah_find_type(priv->ca, priv->port);
rdma_ah_set_dlid(&av, be16_to_cpu(mcast->mcmember.mlid)),
rdma_ah_set_port_num(&av, priv->port);
rdma_ah_set_sl(&av, mcast->mcmember.sl);
rdma_ah_set_static_rate(&av, mcast->mcmember.rate);
rdma_ah_set_grh(&av, &mcast->mcmember.mgid,
be32_to_cpu(mcast->mcmember.flow_label),
0, mcast->mcmember.hop_limit,
mcast->mcmember.traffic_class);
ah = ipoib_create_ah(dev, priv->pd, &av);
if (IS_ERR(ah)) {
ipoib_warn(priv, "ib_address_create failed %ld\n",
-PTR_ERR(ah));
/* use original error */
return PTR_ERR(ah);
}
spin_lock_irq(&priv->lock);
mcast->ah = ah;
spin_unlock_irq(&priv->lock);
ipoib_dbg_mcast(priv, "MGID %pI6 AV %p, LID 0x%04x, SL %d\n",
mcast->mcmember.mgid.raw,
mcast->ah->ah,
be16_to_cpu(mcast->mcmember.mlid),
mcast->mcmember.sl);
/* actually send any queued packets */
netif_tx_lock_bh(dev);
while (!skb_queue_empty(&mcast->pkt_queue)) {
struct sk_buff *skb = skb_dequeue(&mcast->pkt_queue);
netif_tx_unlock_bh(dev);
skb->dev = dev;
ret = dev_queue_xmit(skb);
if (ret)
ipoib_warn(priv, "%s:dev_queue_xmit failed to re-queue packet, ret:%d\n",
__func__, ret);
netif_tx_lock_bh(dev);
}
netif_tx_unlock_bh(dev);
return 0;
}
void ipoib_mcast_carrier_on_task(struct work_struct *work)
{
struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv,
carrier_on_task);
struct ib_port_attr attr;
if (ib_query_port(priv->ca, priv->port, &attr) ||
attr.state != IB_PORT_ACTIVE) {
ipoib_dbg(priv, "Keeping carrier off until IB port is active\n");
return;
}
/*
* Check if can send sendonly MCG's with sendonly-fullmember join state.
* It done here after the successfully join to the broadcast group,
* because the broadcast group must always be joined first and is always
* re-joined if the SM changes substantially.
*/
priv->sm_fullmember_sendonly_support =
ib_sa_sendonly_fullmem_support(&ipoib_sa_client,
priv->ca, priv->port);
/*
* Take rtnl_lock to avoid racing with ipoib_stop() and
* turning the carrier back on while a device is being
* removed. However, ipoib_stop() will attempt to flush
* the workqueue while holding the rtnl lock, so loop
* on trylock until either we get the lock or we see
* FLAG_OPER_UP go away as that signals that we are bailing
* and can safely ignore the carrier on work.
*/
while (!rtnl_trylock()) {
if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
return;
else
msleep(20);
}
if (!ipoib_cm_admin_enabled(priv->dev))
dev_set_mtu(priv->dev, min(priv->mcast_mtu, priv->admin_mtu));
netif_carrier_on(priv->dev);
rtnl_unlock();
}
static int ipoib_mcast_join_complete(int status,
struct ib_sa_multicast *multicast)
{
struct ipoib_mcast *mcast = multicast->context;
struct net_device *dev = mcast->dev;
struct ipoib_dev_priv *priv = ipoib_priv(dev);
ipoib_dbg_mcast(priv, "%sjoin completion for %pI6 (status %d)\n",
test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) ?
"sendonly " : "",
mcast->mcmember.mgid.raw, status);
/* We trap for port events ourselves. */
if (status == -ENETRESET) {
status = 0;
goto out;
}
if (!status)
status = ipoib_mcast_join_finish(mcast, &multicast->rec);
if (!status) {
mcast->backoff = 1;
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
mcast->delay_until = jiffies;
/*
IB/ipoib: Use dedicated workqueues per interface During my recent work on the rtnl lock deadlock in the IPoIB driver, I saw that even once I fixed the apparent races for a single device, as soon as that device had any children, new races popped up. It turns out that this is because no matter how well we protect against races on a single device, the fact that all devices use the same workqueue, and flush_workqueue() flushes *everything* from that workqueue means that we would also have to prevent all races between different devices (for instance, ipoib_mcast_restart_task on interface ib0 can race with ipoib_mcast_flush_dev on interface ib0.8002, resulting in a deadlock on the rtnl_lock). There are several possible solutions to this problem: Make carrier_on_task and mcast_restart_task try to take the rtnl for some set period of time and if they fail, then bail. This runs the real risk of dropping work on the floor, which can end up being its own separate kind of deadlock. Set some global flag in the driver that says some device is in the middle of going down, letting all tasks know to bail. Again, this can drop work on the floor. Or the method this patch attempts to use, which is when we bring an interface up, create a workqueue specifically for that interface, so that when we take it back down, we are flushing only those tasks associated with our interface. In addition, keep the global workqueue, but now limit it to only flush tasks. In this way, the flush tasks can always flush the device specific work queues without having deadlock issues. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:03 +08:00
* Defer carrier on work to priv->wq to avoid a
* deadlock on rtnl_lock here. Requeue our multicast
* work too, which will end up happening right after
* our carrier on task work and will allow us to
* send out all of the non-broadcast joins
*/
if (mcast == priv->broadcast) {
spin_lock_irq(&priv->lock);
IB/ipoib: Use dedicated workqueues per interface During my recent work on the rtnl lock deadlock in the IPoIB driver, I saw that even once I fixed the apparent races for a single device, as soon as that device had any children, new races popped up. It turns out that this is because no matter how well we protect against races on a single device, the fact that all devices use the same workqueue, and flush_workqueue() flushes *everything* from that workqueue means that we would also have to prevent all races between different devices (for instance, ipoib_mcast_restart_task on interface ib0 can race with ipoib_mcast_flush_dev on interface ib0.8002, resulting in a deadlock on the rtnl_lock). There are several possible solutions to this problem: Make carrier_on_task and mcast_restart_task try to take the rtnl for some set period of time and if they fail, then bail. This runs the real risk of dropping work on the floor, which can end up being its own separate kind of deadlock. Set some global flag in the driver that says some device is in the middle of going down, letting all tasks know to bail. Again, this can drop work on the floor. Or the method this patch attempts to use, which is when we bring an interface up, create a workqueue specifically for that interface, so that when we take it back down, we are flushing only those tasks associated with our interface. In addition, keep the global workqueue, but now limit it to only flush tasks. In this way, the flush tasks can always flush the device specific work queues without having deadlock issues. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:03 +08:00
queue_work(priv->wq, &priv->carrier_on_task);
__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
goto out_locked;
}
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
} else {
bool silent_fail =
test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) &&
status == -EINVAL;
if (mcast->logcount < 20) {
if (status == -ETIMEDOUT || status == -EAGAIN ||
silent_fail) {
ipoib_dbg_mcast(priv, "%smulticast join failed for %pI6, status %d\n",
test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) ? "sendonly " : "",
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
mcast->mcmember.mgid.raw, status);
} else {
ipoib_warn(priv, "%smulticast join failed for %pI6, status %d\n",
test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) ? "sendonly " : "",
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
mcast->mcmember.mgid.raw, status);
}
if (!silent_fail)
mcast->logcount++;
}
if (test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) &&
mcast->backoff >= 2) {
/*
* We only retry sendonly joins once before we drop
* the packet and quit trying to deal with the
* group. However, we leave the group in the
* mcast list as an unjoined group. If we want to
* try joining again, we simply queue up a packet
* and restart the join thread. The empty queue
* is why the join thread ignores this group.
*/
mcast->backoff = 1;
netif_tx_lock_bh(dev);
while (!skb_queue_empty(&mcast->pkt_queue)) {
++dev->stats.tx_dropped;
dev_kfree_skb_any(skb_dequeue(&mcast->pkt_queue));
}
netif_tx_unlock_bh(dev);
} else {
spin_lock_irq(&priv->lock);
/* Requeue this join task with a backoff delay */
__ipoib_mcast_schedule_join_thread(priv, mcast, 1);
goto out_locked;
}
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
}
out:
spin_lock_irq(&priv->lock);
out_locked:
/*
* Make sure to set mcast->mc before we clear the busy flag to avoid
* racing with code that checks for BUSY before checking mcast->mc
*/
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
if (status)
mcast->mc = NULL;
else
mcast->mc = multicast;
clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
spin_unlock_irq(&priv->lock);
complete(&mcast->done);
return status;
}
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
/*
* Caller must hold 'priv->lock'
*/
static int ipoib_mcast_join(struct net_device *dev, struct ipoib_mcast *mcast)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
struct ib_sa_multicast *multicast;
struct ib_sa_mcmember_rec rec = {
.join_state = 1
};
ib_sa_comp_mask comp_mask;
int ret = 0;
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
if (!priv->broadcast ||
!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
return -EINVAL;
IB/ipoib: Fix deadlock between ipoib_stop and mcast join flow Before calling ipoib_stop, rtnl_lock should be taken, then the flow clears the IPOIB_FLAG_ADMIN_UP and IPOIB_FLAG_OPER_UP flags, and waits for mcast completion if IPOIB_MCAST_FLAG_BUSY is set. On the other hand, the flow of multicast join task initializes a mcast completion, sets the IPOIB_MCAST_FLAG_BUSY and calls ipoib_mcast_join. If IPOIB_FLAG_OPER_UP flag is not set, this call returns EINVAL without setting the mcast completion and leads to a deadlock. ipoib_stop | | | clear_bit(IPOIB_FLAG_ADMIN_UP) | | | Context Switch | | ipoib_mcast_join_task | | | spin_lock_irq(lock) | | | init_completion(mcast) | | | set_bit(IPOIB_MCAST_FLAG_BUSY) | | | Context Switch | | clear_bit(IPOIB_FLAG_OPER_UP) | | | spin_lock_irqsave(lock) | | | Context Switch | | ipoib_mcast_join | return (-EINVAL) | | | spin_unlock_irq(lock) | | | Context Switch | | ipoib_mcast_dev_flush | wait_for_completion(mcast) | ipoib_stop will wait for mcast completion for ever, and will not release the rtnl_lock. As a result panic occurs with the following trace: [13441.639268] Call Trace: [13441.640150] [<ffffffff8168b579>] schedule+0x29/0x70 [13441.641038] [<ffffffff81688fc9>] schedule_timeout+0x239/0x2d0 [13441.641914] [<ffffffff810bc017>] ? complete+0x47/0x50 [13441.642765] [<ffffffff810a690d>] ? flush_workqueue_prep_pwqs+0x16d/0x200 [13441.643580] [<ffffffff8168b956>] wait_for_completion+0x116/0x170 [13441.644434] [<ffffffff810c4ec0>] ? wake_up_state+0x20/0x20 [13441.645293] [<ffffffffa05af170>] ipoib_mcast_dev_flush+0x150/0x190 [ib_ipoib] [13441.646159] [<ffffffffa05ac967>] ipoib_ib_dev_down+0x37/0x60 [ib_ipoib] [13441.647013] [<ffffffffa05a4805>] ipoib_stop+0x75/0x150 [ib_ipoib] Fixes: 08bc327629cb ("IB/ipoib: fix for rare multicast join race condition") Signed-off-by: Feras Daoud <ferasda@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
2017-03-19 17:18:55 +08:00
init_completion(&mcast->done);
set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
ipoib_dbg_mcast(priv, "joining MGID %pI6\n", mcast->mcmember.mgid.raw);
rec.mgid = mcast->mcmember.mgid;
rec.port_gid = priv->local_gid;
rec.pkey = cpu_to_be16(priv->pkey);
comp_mask =
IB_SA_MCMEMBER_REC_MGID |
IB_SA_MCMEMBER_REC_PORT_GID |
IB_SA_MCMEMBER_REC_PKEY |
IB_SA_MCMEMBER_REC_JOIN_STATE;
if (mcast != priv->broadcast) {
/*
* RFC 4391:
* The MGID MUST use the same P_Key, Q_Key, SL, MTU,
* and HopLimit as those used in the broadcast-GID. The rest
* of attributes SHOULD follow the values used in the
* broadcast-GID as well.
*/
comp_mask |=
IB_SA_MCMEMBER_REC_QKEY |
IB_SA_MCMEMBER_REC_MTU_SELECTOR |
IB_SA_MCMEMBER_REC_MTU |
IB_SA_MCMEMBER_REC_TRAFFIC_CLASS |
IB_SA_MCMEMBER_REC_RATE_SELECTOR |
IB_SA_MCMEMBER_REC_RATE |
IB_SA_MCMEMBER_REC_SL |
IB_SA_MCMEMBER_REC_FLOW_LABEL |
IB_SA_MCMEMBER_REC_HOP_LIMIT;
rec.qkey = priv->broadcast->mcmember.qkey;
rec.mtu_selector = IB_SA_EQ;
rec.mtu = priv->broadcast->mcmember.mtu;
rec.traffic_class = priv->broadcast->mcmember.traffic_class;
rec.rate_selector = IB_SA_EQ;
rec.rate = priv->broadcast->mcmember.rate;
rec.sl = priv->broadcast->mcmember.sl;
rec.flow_label = priv->broadcast->mcmember.flow_label;
rec.hop_limit = priv->broadcast->mcmember.hop_limit;
/*
* Send-only IB Multicast joins work at the core IB layer but
* require specific SM support.
* We can use such joins here only if the current SM supports that feature.
* However, if not, we emulate an Ethernet multicast send,
* which does not require a multicast subscription and will
* still send properly. The most appropriate thing to
* do is to create the group if it doesn't exist as that
* most closely emulates the behavior, from a user space
* application perspective, of Ethernet multicast operation.
*/
if (test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) &&
priv->sm_fullmember_sendonly_support)
/* SM supports sendonly-fullmember, otherwise fallback to full-member */
rec.join_state = SENDONLY_FULLMEMBER_JOIN;
}
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
spin_unlock_irq(&priv->lock);
multicast = ib_sa_join_multicast(&ipoib_sa_client, priv->ca, priv->port,
&rec, comp_mask, GFP_KERNEL,
ipoib_mcast_join_complete, mcast);
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
spin_lock_irq(&priv->lock);
if (IS_ERR(multicast)) {
ret = PTR_ERR(multicast);
ipoib_warn(priv, "ib_sa_join_multicast failed, status %d\n", ret);
/* Requeue this join task with a backoff delay */
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
__ipoib_mcast_schedule_join_thread(priv, mcast, 1);
clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
spin_unlock_irq(&priv->lock);
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
complete(&mcast->done);
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
spin_lock_irq(&priv->lock);
}
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
return 0;
}
void ipoib_mcast_join_task(struct work_struct *work)
{
struct ipoib_dev_priv *priv =
container_of(work, struct ipoib_dev_priv, mcast_task.work);
struct net_device *dev = priv->dev;
struct ib_port_attr port_attr;
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
unsigned long delay_until = 0;
struct ipoib_mcast *mcast = NULL;
if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
return;
if (ib_query_port(priv->ca, priv->port, &port_attr)) {
ipoib_dbg(priv, "ib_query_port() failed\n");
return;
}
if (port_attr.state != IB_PORT_ACTIVE) {
ipoib_dbg(priv, "port state is not ACTIVE (state = %d) suspending join task\n",
port_attr.state);
return;
}
priv->local_lid = port_attr.lid;
netif_addr_lock_bh(dev);
IB/IPoIB: Allow setting the device address In IB networks, and specifically in IPoIB/rdmacm traffic, the device address of an IPoIB interface is used as a means to exchange information between nodes needed for communication. Currently an IPoIB interface will always be created with a device address based on its node GUID without a way to change that. This change adds the ability to set the device address of an IPoIB interface by value. We use the set mac address ndo to do that. The flow should be broken down to two: 1) The GID value is already in the GID table, in this case the interface will be able to set carrier up. 2) The GID value is not yet in the GID table, in this case the interface won't try to join the multicast group and will wait (listen on GID_CHANGE event) until the GID is inserted. In order to track those changes, we add a new flag: * IPOIB_FLAG_DEV_ADDR_SET. When set, it means the dev_addr is a based on a value in the gid table. this bit will be cleared upon a dev_addr change triggered by the user and set after validation. Per IB spec the port GUID can't change if the module is loaded. port GUID is the basis for GID at index 0 which is the basis for the default device address of a ipoib interface. The issue is that there are devices that don't follow the spec, they change the port GUID while HCA is powered on, so in order not to break userspace applications. We need to check if the user wanted to control the device address and we assume that if he sets the device address back to be based on GID index 0, he no longer wishs to control it. In order to track this, we add an additional flag: * IPOIB_FLAG_DEV_ADDR_CTRL When setting the device address, there is no validation of the upper twelve bytes of the device address (flags, qpn, subnet prefix) as those bytes are not under the control of the user. Signed-off-by: Mark Bloch <markb@mellanox.com> Reviewed-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-05-18 21:42:43 +08:00
if (!test_bit(IPOIB_FLAG_DEV_ADDR_SET, &priv->flags)) {
netif_addr_unlock_bh(dev);
IB/IPoIB: Allow setting the device address In IB networks, and specifically in IPoIB/rdmacm traffic, the device address of an IPoIB interface is used as a means to exchange information between nodes needed for communication. Currently an IPoIB interface will always be created with a device address based on its node GUID without a way to change that. This change adds the ability to set the device address of an IPoIB interface by value. We use the set mac address ndo to do that. The flow should be broken down to two: 1) The GID value is already in the GID table, in this case the interface will be able to set carrier up. 2) The GID value is not yet in the GID table, in this case the interface won't try to join the multicast group and will wait (listen on GID_CHANGE event) until the GID is inserted. In order to track those changes, we add a new flag: * IPOIB_FLAG_DEV_ADDR_SET. When set, it means the dev_addr is a based on a value in the gid table. this bit will be cleared upon a dev_addr change triggered by the user and set after validation. Per IB spec the port GUID can't change if the module is loaded. port GUID is the basis for GID at index 0 which is the basis for the default device address of a ipoib interface. The issue is that there are devices that don't follow the spec, they change the port GUID while HCA is powered on, so in order not to break userspace applications. We need to check if the user wanted to control the device address and we assume that if he sets the device address back to be based on GID index 0, he no longer wishs to control it. In order to track this, we add an additional flag: * IPOIB_FLAG_DEV_ADDR_CTRL When setting the device address, there is no validation of the upper twelve bytes of the device address (flags, qpn, subnet prefix) as those bytes are not under the control of the user. Signed-off-by: Mark Bloch <markb@mellanox.com> Reviewed-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-05-18 21:42:43 +08:00
return;
}
netif_addr_unlock_bh(dev);
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
spin_lock_irq(&priv->lock);
if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
goto out;
if (!priv->broadcast) {
struct ipoib_mcast *broadcast;
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
broadcast = ipoib_mcast_alloc(dev, 0);
if (!broadcast) {
ipoib_warn(priv, "failed to allocate broadcast group\n");
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
/*
* Restart us after a 1 second delay to retry
* creating our broadcast group and attaching to
* it. Until this succeeds, this ipoib dev is
* completely stalled (multicast wise).
*/
__ipoib_mcast_schedule_join_thread(priv, NULL, 1);
goto out;
}
memcpy(broadcast->mcmember.mgid.raw, priv->dev->broadcast + 4,
sizeof (union ib_gid));
priv->broadcast = broadcast;
__ipoib_mcast_add(dev, priv->broadcast);
}
if (!test_bit(IPOIB_MCAST_FLAG_ATTACHED, &priv->broadcast->flags)) {
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
if (IS_ERR_OR_NULL(priv->broadcast->mc) &&
!test_bit(IPOIB_MCAST_FLAG_BUSY, &priv->broadcast->flags)) {
mcast = priv->broadcast;
if (mcast->backoff > 1 &&
time_before(jiffies, mcast->delay_until)) {
delay_until = mcast->delay_until;
mcast = NULL;
}
}
goto out;
}
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
/*
* We'll never get here until the broadcast group is both allocated
* and attached
*/
list_for_each_entry(mcast, &priv->multicast_list, list) {
if (IS_ERR_OR_NULL(mcast->mc) &&
!test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags) &&
(!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) ||
!skb_queue_empty(&mcast->pkt_queue))) {
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
if (mcast->backoff == 1 ||
time_after_eq(jiffies, mcast->delay_until)) {
/* Found the next unjoined group */
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
if (ipoib_mcast_join(dev, mcast)) {
spin_unlock_irq(&priv->lock);
return;
}
} else if (!delay_until ||
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
time_before(mcast->delay_until, delay_until))
delay_until = mcast->delay_until;
}
}
mcast = NULL;
ipoib_dbg_mcast(priv, "successfully started all multicast joins\n");
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
out:
if (delay_until) {
cancel_delayed_work(&priv->mcast_task);
queue_delayed_work(priv->wq, &priv->mcast_task,
delay_until - jiffies);
}
IB/ipoib: Fix deadlock between ipoib_stop and mcast join flow Before calling ipoib_stop, rtnl_lock should be taken, then the flow clears the IPOIB_FLAG_ADMIN_UP and IPOIB_FLAG_OPER_UP flags, and waits for mcast completion if IPOIB_MCAST_FLAG_BUSY is set. On the other hand, the flow of multicast join task initializes a mcast completion, sets the IPOIB_MCAST_FLAG_BUSY and calls ipoib_mcast_join. If IPOIB_FLAG_OPER_UP flag is not set, this call returns EINVAL without setting the mcast completion and leads to a deadlock. ipoib_stop | | | clear_bit(IPOIB_FLAG_ADMIN_UP) | | | Context Switch | | ipoib_mcast_join_task | | | spin_lock_irq(lock) | | | init_completion(mcast) | | | set_bit(IPOIB_MCAST_FLAG_BUSY) | | | Context Switch | | clear_bit(IPOIB_FLAG_OPER_UP) | | | spin_lock_irqsave(lock) | | | Context Switch | | ipoib_mcast_join | return (-EINVAL) | | | spin_unlock_irq(lock) | | | Context Switch | | ipoib_mcast_dev_flush | wait_for_completion(mcast) | ipoib_stop will wait for mcast completion for ever, and will not release the rtnl_lock. As a result panic occurs with the following trace: [13441.639268] Call Trace: [13441.640150] [<ffffffff8168b579>] schedule+0x29/0x70 [13441.641038] [<ffffffff81688fc9>] schedule_timeout+0x239/0x2d0 [13441.641914] [<ffffffff810bc017>] ? complete+0x47/0x50 [13441.642765] [<ffffffff810a690d>] ? flush_workqueue_prep_pwqs+0x16d/0x200 [13441.643580] [<ffffffff8168b956>] wait_for_completion+0x116/0x170 [13441.644434] [<ffffffff810c4ec0>] ? wake_up_state+0x20/0x20 [13441.645293] [<ffffffffa05af170>] ipoib_mcast_dev_flush+0x150/0x190 [ib_ipoib] [13441.646159] [<ffffffffa05ac967>] ipoib_ib_dev_down+0x37/0x60 [ib_ipoib] [13441.647013] [<ffffffffa05a4805>] ipoib_stop+0x75/0x150 [ib_ipoib] Fixes: 08bc327629cb ("IB/ipoib: fix for rare multicast join race condition") Signed-off-by: Feras Daoud <ferasda@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
2017-03-19 17:18:55 +08:00
if (mcast)
IB/ipoib: fix for rare multicast join race condition A narrow window for race condition still exist between multicast join thread and *dev_flush workers. A kernel crash caused by prolong erratic link state changes was observed (most likely a faulty cabling): [167275.656270] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 [167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib] [167275.674443] PGD 0 [167275.677373] Oops: 0000 [#1] SMP ... [167275.977530] Call Trace: [167275.982225] [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib] [167275.992024] [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490 [ib_ipoib] [167276.002149] [<ffffffff8109d5fb>] process_one_work+0x17b/0x470 [167276.010754] [<ffffffff8109e3cb>] worker_thread+0x11b/0x400 [167276.019088] [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400 [167276.027737] [<ffffffff810a5aef>] kthread+0xcf/0xe0 Here was a hit spot: ipoib_mcast_join() { .............. rec.qkey = priv->broadcast->mcmember.qkey; ^^^^^^^ ..... } Proposed patch should prevent multicast join task to continue if link state change is detected. Signed-off-by: Alex Estrin <alex.estrin@intel.com> Changes from v4: - as suggested by Doug Ledford, optimized spinlock usage, i.e. ipoib_mcast_join() is called with lock held. Changes from v3: - sync with priv->lock before flag check. Chages from v2: - Move check for OPER_UP flag state to mcast_join() to ensure no event worker is in progress. - minor style fixes. Changes from v1: - No need to lock again if error detected. Signed-off-by: Doug Ledford <dledford@redhat.com>
2016-02-12 05:30:51 +08:00
ipoib_mcast_join(dev, mcast);
IB/ipoib: Fix deadlock between ipoib_stop and mcast join flow Before calling ipoib_stop, rtnl_lock should be taken, then the flow clears the IPOIB_FLAG_ADMIN_UP and IPOIB_FLAG_OPER_UP flags, and waits for mcast completion if IPOIB_MCAST_FLAG_BUSY is set. On the other hand, the flow of multicast join task initializes a mcast completion, sets the IPOIB_MCAST_FLAG_BUSY and calls ipoib_mcast_join. If IPOIB_FLAG_OPER_UP flag is not set, this call returns EINVAL without setting the mcast completion and leads to a deadlock. ipoib_stop | | | clear_bit(IPOIB_FLAG_ADMIN_UP) | | | Context Switch | | ipoib_mcast_join_task | | | spin_lock_irq(lock) | | | init_completion(mcast) | | | set_bit(IPOIB_MCAST_FLAG_BUSY) | | | Context Switch | | clear_bit(IPOIB_FLAG_OPER_UP) | | | spin_lock_irqsave(lock) | | | Context Switch | | ipoib_mcast_join | return (-EINVAL) | | | spin_unlock_irq(lock) | | | Context Switch | | ipoib_mcast_dev_flush | wait_for_completion(mcast) | ipoib_stop will wait for mcast completion for ever, and will not release the rtnl_lock. As a result panic occurs with the following trace: [13441.639268] Call Trace: [13441.640150] [<ffffffff8168b579>] schedule+0x29/0x70 [13441.641038] [<ffffffff81688fc9>] schedule_timeout+0x239/0x2d0 [13441.641914] [<ffffffff810bc017>] ? complete+0x47/0x50 [13441.642765] [<ffffffff810a690d>] ? flush_workqueue_prep_pwqs+0x16d/0x200 [13441.643580] [<ffffffff8168b956>] wait_for_completion+0x116/0x170 [13441.644434] [<ffffffff810c4ec0>] ? wake_up_state+0x20/0x20 [13441.645293] [<ffffffffa05af170>] ipoib_mcast_dev_flush+0x150/0x190 [ib_ipoib] [13441.646159] [<ffffffffa05ac967>] ipoib_ib_dev_down+0x37/0x60 [ib_ipoib] [13441.647013] [<ffffffffa05a4805>] ipoib_stop+0x75/0x150 [ib_ipoib] Fixes: 08bc327629cb ("IB/ipoib: fix for rare multicast join race condition") Signed-off-by: Feras Daoud <ferasda@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
2017-03-19 17:18:55 +08:00
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
spin_unlock_irq(&priv->lock);
}
void ipoib_mcast_start_thread(struct net_device *dev)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
unsigned long flags;
ipoib_dbg_mcast(priv, "starting multicast thread\n");
spin_lock_irqsave(&priv->lock, flags);
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
spin_unlock_irqrestore(&priv->lock, flags);
}
int ipoib_mcast_stop_thread(struct net_device *dev)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
ipoib_dbg_mcast(priv, "stopping multicast thread\n");
cancel_delayed_work_sync(&priv->mcast_task);
return 0;
}
static int ipoib_mcast_leave(struct net_device *dev, struct ipoib_mcast *mcast)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
struct rdma_netdev *rn = netdev_priv(dev);
int ret = 0;
if (test_and_clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
ipoib_warn(priv, "ipoib_mcast_leave on an in-flight join\n");
if (!IS_ERR_OR_NULL(mcast->mc))
ib_sa_free_multicast(mcast->mc);
if (test_and_clear_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
ipoib_dbg_mcast(priv, "leaving MGID %pI6\n",
mcast->mcmember.mgid.raw);
/* Remove ourselves from the multicast group */
ret = rn->detach_mcast(dev, priv->ca, &mcast->mcmember.mgid,
be16_to_cpu(mcast->mcmember.mlid));
if (ret)
ipoib_warn(priv, "ib_detach_mcast failed (result = %d)\n", ret);
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
} else if (!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags))
ipoib_dbg(priv, "leaving with no mcmember but not a "
"SENDONLY join\n");
return 0;
}
/*
* Check if the multicast group is sendonly. If so remove it from the maps
* and add to the remove list
*/
void ipoib_check_and_add_mcast_sendonly(struct ipoib_dev_priv *priv, u8 *mgid,
struct list_head *remove_list)
{
/* Is this multicast ? */
if (*mgid == 0xff) {
struct ipoib_mcast *mcast = __ipoib_mcast_find(priv->dev, mgid);
if (mcast && test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)) {
list_del(&mcast->list);
rb_erase(&mcast->rb_node, &priv->multicast_tree);
list_add_tail(&mcast->list, remove_list);
}
}
}
void ipoib_mcast_remove_list(struct list_head *remove_list)
{
struct ipoib_mcast *mcast, *tmcast;
/*
* make sure the in-flight joins have finished before we attempt
* to leave
*/
list_for_each_entry_safe(mcast, tmcast, remove_list, list)
if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
wait_for_completion(&mcast->done);
list_for_each_entry_safe(mcast, tmcast, remove_list, list) {
ipoib_mcast_leave(mcast->dev, mcast);
ipoib_mcast_free(mcast);
}
}
IPoIB: Use a private hash table for path lookup in xmit path Dave Miller <davem@davemloft.net> provided a detailed description of why the way IPoIB is using neighbours for its own ipoib_neigh struct is buggy: Any time an ipoib_neigh is changed, a sequence like the following is made: spin_lock_irqsave(&priv->lock, flags); /* * It's safe to call ipoib_put_ah() inside * priv->lock here, because we know that * path->ah will always hold one more reference, * so ipoib_put_ah() will never do more than * decrement the ref count. */ if (neigh->ah) ipoib_put_ah(neigh->ah); list_del(&neigh->list); ipoib_neigh_free(dev, neigh); spin_unlock_irqrestore(&priv->lock, flags); ipoib_path_lookup(skb, n, dev); This doesn't work, because you're leaving a stale pointer to the freed up ipoib_neigh in the special neigh->ha pointer cookie. Yes, it even fails with all the locking done to protect _changes_ to *ipoib_neigh(n), and with the code in ipoib_neigh_free() that NULLs out the pointer. The core issue is that read side calls to *to_ipoib_neigh(n) are not being synchronized at all, they are performed without any locking. So whether we hold the lock or not when making changes to *ipoib_neigh(n) you still can have threads see references to freed up ipoib_neigh objects. cpu 1 cpu 2 n = *ipoib_neigh() *ipoib_neigh() = NULL kfree(n) n->foo == OOPS [..] Perhaps the ipoib code can have a private path database it manages entirely itself, which holds all the necessary information and is looked up by some generic key which is available easily at transmit time and does not involve generic neighbour entries. See <http://marc.info/?l=linux-rdma&m=132812793105624&w=2> and <http://marc.info/?l=linux-rdma&w=2&r=1&s=allows+references+to+freed+memory&q=b> for the full discussion. This patch aims to solve the race conditions found in the IPoIB driver. The patch removes the connection between the core networking neighbour structure and the ipoib_neigh structure. In addition to avoiding the race described above, it allows us to handle SKBs carrying IP packets that don't have any associated neighbour. We add an ipoib_neigh hash table with N buckets where the key is the destination hardware address. The ipoib_neigh is fetched from the hash table and instead of the stashed location in the neighbour structure. The hash table uses both RCU and reference counting to guarantee that no ipoib_neigh instance is ever deleted while in use. Fetching the ipoib_neigh structure instance from the hash also makes the special code in ipoib_start_xmit that handles remote and local bonding failover redundant. Aged ipoib_neigh instances are deleted by a garbage collection task that runs every M seconds and deletes every ipoib_neigh instance that was idle for at least 2*M seconds. The deletion is safe since the ipoib_neigh instances are protected using RCU and reference count mechanisms. The number of buckets (N) and frequency of running the GC thread (M), are taken from the exported arb_tbl. Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com> Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Roland Dreier <roland@purestorage.com>
2012-07-25 01:05:22 +08:00
void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
struct rdma_netdev *rn = netdev_priv(dev);
struct ipoib_mcast *mcast;
unsigned long flags;
IPoIB: Use a private hash table for path lookup in xmit path Dave Miller <davem@davemloft.net> provided a detailed description of why the way IPoIB is using neighbours for its own ipoib_neigh struct is buggy: Any time an ipoib_neigh is changed, a sequence like the following is made: spin_lock_irqsave(&priv->lock, flags); /* * It's safe to call ipoib_put_ah() inside * priv->lock here, because we know that * path->ah will always hold one more reference, * so ipoib_put_ah() will never do more than * decrement the ref count. */ if (neigh->ah) ipoib_put_ah(neigh->ah); list_del(&neigh->list); ipoib_neigh_free(dev, neigh); spin_unlock_irqrestore(&priv->lock, flags); ipoib_path_lookup(skb, n, dev); This doesn't work, because you're leaving a stale pointer to the freed up ipoib_neigh in the special neigh->ha pointer cookie. Yes, it even fails with all the locking done to protect _changes_ to *ipoib_neigh(n), and with the code in ipoib_neigh_free() that NULLs out the pointer. The core issue is that read side calls to *to_ipoib_neigh(n) are not being synchronized at all, they are performed without any locking. So whether we hold the lock or not when making changes to *ipoib_neigh(n) you still can have threads see references to freed up ipoib_neigh objects. cpu 1 cpu 2 n = *ipoib_neigh() *ipoib_neigh() = NULL kfree(n) n->foo == OOPS [..] Perhaps the ipoib code can have a private path database it manages entirely itself, which holds all the necessary information and is looked up by some generic key which is available easily at transmit time and does not involve generic neighbour entries. See <http://marc.info/?l=linux-rdma&m=132812793105624&w=2> and <http://marc.info/?l=linux-rdma&w=2&r=1&s=allows+references+to+freed+memory&q=b> for the full discussion. This patch aims to solve the race conditions found in the IPoIB driver. The patch removes the connection between the core networking neighbour structure and the ipoib_neigh structure. In addition to avoiding the race described above, it allows us to handle SKBs carrying IP packets that don't have any associated neighbour. We add an ipoib_neigh hash table with N buckets where the key is the destination hardware address. The ipoib_neigh is fetched from the hash table and instead of the stashed location in the neighbour structure. The hash table uses both RCU and reference counting to guarantee that no ipoib_neigh instance is ever deleted while in use. Fetching the ipoib_neigh structure instance from the hash also makes the special code in ipoib_start_xmit that handles remote and local bonding failover redundant. Aged ipoib_neigh instances are deleted by a garbage collection task that runs every M seconds and deletes every ipoib_neigh instance that was idle for at least 2*M seconds. The deletion is safe since the ipoib_neigh instances are protected using RCU and reference count mechanisms. The number of buckets (N) and frequency of running the GC thread (M), are taken from the exported arb_tbl. Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com> Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Roland Dreier <roland@purestorage.com>
2012-07-25 01:05:22 +08:00
void *mgid = daddr + 4;
spin_lock_irqsave(&priv->lock, flags);
if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags) ||
!priv->broadcast ||
!test_bit(IPOIB_MCAST_FLAG_ATTACHED, &priv->broadcast->flags)) {
++dev->stats.tx_dropped;
dev_kfree_skb_any(skb);
goto unlock;
}
mcast = __ipoib_mcast_find(dev, mgid);
if (!mcast || !mcast->ah) {
if (!mcast) {
/* Let's create a new send only group now */
ipoib_dbg_mcast(priv, "setting up send only multicast group for %pI6\n",
mgid);
mcast = ipoib_mcast_alloc(dev, 0);
if (!mcast) {
ipoib_warn(priv, "unable to allocate memory "
"for multicast structure\n");
++dev->stats.tx_dropped;
dev_kfree_skb_any(skb);
goto unlock;
}
set_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags);
memcpy(mcast->mcmember.mgid.raw, mgid,
sizeof (union ib_gid));
__ipoib_mcast_add(dev, mcast);
list_add_tail(&mcast->list, &priv->multicast_list);
}
if (skb_queue_len(&mcast->pkt_queue) < IPOIB_MAX_MCAST_QUEUE) {
/* put pseudoheader back on for next time */
skb_push(skb, sizeof(struct ipoib_pseudo_header));
skb_queue_tail(&mcast->pkt_queue, skb);
} else {
++dev->stats.tx_dropped;
dev_kfree_skb_any(skb);
}
if (!test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags)) {
__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
}
} else {
IPoIB: Use a private hash table for path lookup in xmit path Dave Miller <davem@davemloft.net> provided a detailed description of why the way IPoIB is using neighbours for its own ipoib_neigh struct is buggy: Any time an ipoib_neigh is changed, a sequence like the following is made: spin_lock_irqsave(&priv->lock, flags); /* * It's safe to call ipoib_put_ah() inside * priv->lock here, because we know that * path->ah will always hold one more reference, * so ipoib_put_ah() will never do more than * decrement the ref count. */ if (neigh->ah) ipoib_put_ah(neigh->ah); list_del(&neigh->list); ipoib_neigh_free(dev, neigh); spin_unlock_irqrestore(&priv->lock, flags); ipoib_path_lookup(skb, n, dev); This doesn't work, because you're leaving a stale pointer to the freed up ipoib_neigh in the special neigh->ha pointer cookie. Yes, it even fails with all the locking done to protect _changes_ to *ipoib_neigh(n), and with the code in ipoib_neigh_free() that NULLs out the pointer. The core issue is that read side calls to *to_ipoib_neigh(n) are not being synchronized at all, they are performed without any locking. So whether we hold the lock or not when making changes to *ipoib_neigh(n) you still can have threads see references to freed up ipoib_neigh objects. cpu 1 cpu 2 n = *ipoib_neigh() *ipoib_neigh() = NULL kfree(n) n->foo == OOPS [..] Perhaps the ipoib code can have a private path database it manages entirely itself, which holds all the necessary information and is looked up by some generic key which is available easily at transmit time and does not involve generic neighbour entries. See <http://marc.info/?l=linux-rdma&m=132812793105624&w=2> and <http://marc.info/?l=linux-rdma&w=2&r=1&s=allows+references+to+freed+memory&q=b> for the full discussion. This patch aims to solve the race conditions found in the IPoIB driver. The patch removes the connection between the core networking neighbour structure and the ipoib_neigh structure. In addition to avoiding the race described above, it allows us to handle SKBs carrying IP packets that don't have any associated neighbour. We add an ipoib_neigh hash table with N buckets where the key is the destination hardware address. The ipoib_neigh is fetched from the hash table and instead of the stashed location in the neighbour structure. The hash table uses both RCU and reference counting to guarantee that no ipoib_neigh instance is ever deleted while in use. Fetching the ipoib_neigh structure instance from the hash also makes the special code in ipoib_start_xmit that handles remote and local bonding failover redundant. Aged ipoib_neigh instances are deleted by a garbage collection task that runs every M seconds and deletes every ipoib_neigh instance that was idle for at least 2*M seconds. The deletion is safe since the ipoib_neigh instances are protected using RCU and reference count mechanisms. The number of buckets (N) and frequency of running the GC thread (M), are taken from the exported arb_tbl. Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com> Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Roland Dreier <roland@purestorage.com>
2012-07-25 01:05:22 +08:00
struct ipoib_neigh *neigh;
spin_unlock_irqrestore(&priv->lock, flags);
neigh = ipoib_neigh_get(dev, daddr);
spin_lock_irqsave(&priv->lock, flags);
if (!neigh) {
neigh = ipoib_neigh_alloc(daddr, dev);
if (neigh) {
kref_get(&mcast->ah->ref);
neigh->ah = mcast->ah;
list_add_tail(&neigh->list, &mcast->neigh_list);
}
}
spin_unlock_irqrestore(&priv->lock, flags);
mcast->ah->last_send = rn->send(dev, skb, mcast->ah->ah,
IB_MULTICAST_QPN);
IPoIB: Use a private hash table for path lookup in xmit path Dave Miller <davem@davemloft.net> provided a detailed description of why the way IPoIB is using neighbours for its own ipoib_neigh struct is buggy: Any time an ipoib_neigh is changed, a sequence like the following is made: spin_lock_irqsave(&priv->lock, flags); /* * It's safe to call ipoib_put_ah() inside * priv->lock here, because we know that * path->ah will always hold one more reference, * so ipoib_put_ah() will never do more than * decrement the ref count. */ if (neigh->ah) ipoib_put_ah(neigh->ah); list_del(&neigh->list); ipoib_neigh_free(dev, neigh); spin_unlock_irqrestore(&priv->lock, flags); ipoib_path_lookup(skb, n, dev); This doesn't work, because you're leaving a stale pointer to the freed up ipoib_neigh in the special neigh->ha pointer cookie. Yes, it even fails with all the locking done to protect _changes_ to *ipoib_neigh(n), and with the code in ipoib_neigh_free() that NULLs out the pointer. The core issue is that read side calls to *to_ipoib_neigh(n) are not being synchronized at all, they are performed without any locking. So whether we hold the lock or not when making changes to *ipoib_neigh(n) you still can have threads see references to freed up ipoib_neigh objects. cpu 1 cpu 2 n = *ipoib_neigh() *ipoib_neigh() = NULL kfree(n) n->foo == OOPS [..] Perhaps the ipoib code can have a private path database it manages entirely itself, which holds all the necessary information and is looked up by some generic key which is available easily at transmit time and does not involve generic neighbour entries. See <http://marc.info/?l=linux-rdma&m=132812793105624&w=2> and <http://marc.info/?l=linux-rdma&w=2&r=1&s=allows+references+to+freed+memory&q=b> for the full discussion. This patch aims to solve the race conditions found in the IPoIB driver. The patch removes the connection between the core networking neighbour structure and the ipoib_neigh structure. In addition to avoiding the race described above, it allows us to handle SKBs carrying IP packets that don't have any associated neighbour. We add an ipoib_neigh hash table with N buckets where the key is the destination hardware address. The ipoib_neigh is fetched from the hash table and instead of the stashed location in the neighbour structure. The hash table uses both RCU and reference counting to guarantee that no ipoib_neigh instance is ever deleted while in use. Fetching the ipoib_neigh structure instance from the hash also makes the special code in ipoib_start_xmit that handles remote and local bonding failover redundant. Aged ipoib_neigh instances are deleted by a garbage collection task that runs every M seconds and deletes every ipoib_neigh instance that was idle for at least 2*M seconds. The deletion is safe since the ipoib_neigh instances are protected using RCU and reference count mechanisms. The number of buckets (N) and frequency of running the GC thread (M), are taken from the exported arb_tbl. Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com> Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Roland Dreier <roland@purestorage.com>
2012-07-25 01:05:22 +08:00
if (neigh)
ipoib_neigh_put(neigh);
return;
}
unlock:
spin_unlock_irqrestore(&priv->lock, flags);
}
void ipoib_mcast_dev_flush(struct net_device *dev)
{
struct ipoib_dev_priv *priv = ipoib_priv(dev);
LIST_HEAD(remove_list);
struct ipoib_mcast *mcast, *tmcast;
unsigned long flags;
mutex_lock(&priv->mcast_mutex);
ipoib_dbg_mcast(priv, "flushing multicast list\n");
spin_lock_irqsave(&priv->lock, flags);
list_for_each_entry_safe(mcast, tmcast, &priv->multicast_list, list) {
list_del(&mcast->list);
rb_erase(&mcast->rb_node, &priv->multicast_tree);
list_add_tail(&mcast->list, &remove_list);
}
if (priv->broadcast) {
rb_erase(&priv->broadcast->rb_node, &priv->multicast_tree);
list_add_tail(&priv->broadcast->list, &remove_list);
priv->broadcast = NULL;
}
spin_unlock_irqrestore(&priv->lock, flags);
ipoib_mcast_remove_list(&remove_list);
mutex_unlock(&priv->mcast_mutex);
}
static int ipoib_mcast_addr_is_valid(const u8 *addr, const u8 *broadcast)
{
/* reserved QPN, prefix, scope */
if (memcmp(addr, broadcast, 6))
return 0;
/* signature lower, pkey */
if (memcmp(addr + 7, broadcast + 7, 3))
return 0;
return 1;
}
void ipoib_mcast_restart_task(struct work_struct *work)
{
struct ipoib_dev_priv *priv =
container_of(work, struct ipoib_dev_priv, restart_task);
struct net_device *dev = priv->dev;
struct netdev_hw_addr *ha;
struct ipoib_mcast *mcast, *tmcast;
LIST_HEAD(remove_list);
unsigned long flags;
IPoIB: Allow setting policy to ignore multicast groups The kernel IB stack allows (through the RDMA CM) userspace applications to join and use multicast groups from the IPoIB MGID range. This allows multicast traffic to be handled directly from userspace QPs, without going through the kernel stack, which gives better performance for some applications. However, to fully interoperate with IP multicast, such userspace applications need to participate in IGMP reports and queries, or else routers may not forward the multicast traffic to the system where the application is running. The simplest way to do this is to share the kernel IGMP implementation by using the IP_ADD_MEMBERSHIP option to join multicast groups that are being handled directly in userspace. However, in such cases, the actual multicast traffic should not also be handled by the IPoIB interface, because that would burn resources handling multicast packets that will just be discarded in the kernel. To handle this, this patch adds lookup on the database used for IB multicast group reference counting when IPoIB is joining multicast groups, and if a multicast group is already handled by user space, then the IPoIB kernel driver ignores the group. This is controlled by a per-interface policy flag. When the flag is set, IPoIB will not join and attach its QP to a multicast group which already has an entry in the database; when the flag is cleared, IPoIB will behave as before this change. For each IPoIB interface, the /sys/class/net/$intf/umcast attribute controls the policy flag. The default value is off/0. Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com> Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-10-08 16:13:00 +08:00
struct ib_sa_mcmember_rec rec;
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
/*
* shortcut...on shutdown flush is called next, just
* let it do all the work
*/
return;
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
ipoib_dbg_mcast(priv, "restarting multicast task\n");
[NET]: Add netif_tx_lock Various drivers use xmit_lock internally to synchronise with their transmission routines. They do so without setting xmit_lock_owner. This is fine as long as netpoll is not in use. With netpoll it is possible for deadlocks to occur if xmit_lock_owner isn't set. This is because if a printk occurs while xmit_lock is held and xmit_lock_owner is not set can cause netpoll to attempt to take xmit_lock recursively. While it is possible to resolve this by getting netpoll to use trylock, it is suboptimal because netpoll's sole objective is to maximise the chance of getting the printk out on the wire. So delaying or dropping the message is to be avoided as much as possible. So the only alternative is to always set xmit_lock_owner. The following patch does this by introducing the netif_tx_lock family of functions that take care of setting/unsetting xmit_lock_owner. I renamed xmit_lock to _xmit_lock to indicate that it should not be used directly. I didn't provide irq versions of the netif_tx_lock functions since xmit_lock is meant to be a BH-disabling lock. This is pretty much a straight text substitution except for a small bug fix in winbond. It currently uses netif_stop_queue/spin_unlock_wait to stop transmission. This is unsafe as an IRQ can potentially wake up the queue. So it is safer to use netif_tx_disable. The hamradio bits used spin_lock_irq but it is unnecessary as xmit_lock must never be taken in an IRQ handler. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-10 03:20:56 +08:00
local_irq_save(flags);
netif_addr_lock(dev);
spin_lock(&priv->lock);
/*
* Unfortunately, the networking core only gives us a list of all of
* the multicast hardware addresses. We need to figure out which ones
* are new and which ones have been removed
*/
/* Clear out the found flag */
list_for_each_entry(mcast, &priv->multicast_list, list)
clear_bit(IPOIB_MCAST_FLAG_FOUND, &mcast->flags);
/* Mark all of the entries that are found or don't exist */
netdev_for_each_mc_addr(ha, dev) {
union ib_gid mgid;
if (!ipoib_mcast_addr_is_valid(ha->addr, dev->broadcast))
continue;
memcpy(mgid.raw, ha->addr + 4, sizeof mgid);
mcast = __ipoib_mcast_find(dev, &mgid);
if (!mcast || test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)) {
struct ipoib_mcast *nmcast;
IPoIB: Allow setting policy to ignore multicast groups The kernel IB stack allows (through the RDMA CM) userspace applications to join and use multicast groups from the IPoIB MGID range. This allows multicast traffic to be handled directly from userspace QPs, without going through the kernel stack, which gives better performance for some applications. However, to fully interoperate with IP multicast, such userspace applications need to participate in IGMP reports and queries, or else routers may not forward the multicast traffic to the system where the application is running. The simplest way to do this is to share the kernel IGMP implementation by using the IP_ADD_MEMBERSHIP option to join multicast groups that are being handled directly in userspace. However, in such cases, the actual multicast traffic should not also be handled by the IPoIB interface, because that would burn resources handling multicast packets that will just be discarded in the kernel. To handle this, this patch adds lookup on the database used for IB multicast group reference counting when IPoIB is joining multicast groups, and if a multicast group is already handled by user space, then the IPoIB kernel driver ignores the group. This is controlled by a per-interface policy flag. When the flag is set, IPoIB will not join and attach its QP to a multicast group which already has an entry in the database; when the flag is cleared, IPoIB will behave as before this change. For each IPoIB interface, the /sys/class/net/$intf/umcast attribute controls the policy flag. The default value is off/0. Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com> Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-10-08 16:13:00 +08:00
/* ignore group which is directly joined by userspace */
if (test_bit(IPOIB_FLAG_UMCAST, &priv->flags) &&
!ib_sa_get_mcmember_rec(priv->ca, priv->port, &mgid, &rec)) {
ipoib_dbg_mcast(priv, "ignoring multicast entry for mgid %pI6\n",
mgid.raw);
IPoIB: Allow setting policy to ignore multicast groups The kernel IB stack allows (through the RDMA CM) userspace applications to join and use multicast groups from the IPoIB MGID range. This allows multicast traffic to be handled directly from userspace QPs, without going through the kernel stack, which gives better performance for some applications. However, to fully interoperate with IP multicast, such userspace applications need to participate in IGMP reports and queries, or else routers may not forward the multicast traffic to the system where the application is running. The simplest way to do this is to share the kernel IGMP implementation by using the IP_ADD_MEMBERSHIP option to join multicast groups that are being handled directly in userspace. However, in such cases, the actual multicast traffic should not also be handled by the IPoIB interface, because that would burn resources handling multicast packets that will just be discarded in the kernel. To handle this, this patch adds lookup on the database used for IB multicast group reference counting when IPoIB is joining multicast groups, and if a multicast group is already handled by user space, then the IPoIB kernel driver ignores the group. This is controlled by a per-interface policy flag. When the flag is set, IPoIB will not join and attach its QP to a multicast group which already has an entry in the database; when the flag is cleared, IPoIB will behave as before this change. For each IPoIB interface, the /sys/class/net/$intf/umcast attribute controls the policy flag. The default value is off/0. Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com> Signed-off-by: Roland Dreier <rolandd@cisco.com>
2007-10-08 16:13:00 +08:00
continue;
}
/* Not found or send-only group, let's add a new entry */
ipoib_dbg_mcast(priv, "adding multicast entry for mgid %pI6\n",
mgid.raw);
nmcast = ipoib_mcast_alloc(dev, 0);
if (!nmcast) {
ipoib_warn(priv, "unable to allocate memory for multicast structure\n");
continue;
}
set_bit(IPOIB_MCAST_FLAG_FOUND, &nmcast->flags);
nmcast->mcmember.mgid = mgid;
if (mcast) {
/* Destroy the send only entry */
list_move_tail(&mcast->list, &remove_list);
rb_replace_node(&mcast->rb_node,
&nmcast->rb_node,
&priv->multicast_tree);
} else
__ipoib_mcast_add(dev, nmcast);
list_add_tail(&nmcast->list, &priv->multicast_list);
}
if (mcast)
set_bit(IPOIB_MCAST_FLAG_FOUND, &mcast->flags);
}
/* Remove all of the entries don't exist anymore */
list_for_each_entry_safe(mcast, tmcast, &priv->multicast_list, list) {
if (!test_bit(IPOIB_MCAST_FLAG_FOUND, &mcast->flags) &&
!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)) {
ipoib_dbg_mcast(priv, "deleting multicast group %pI6\n",
mcast->mcmember.mgid.raw);
rb_erase(&mcast->rb_node, &priv->multicast_tree);
/* Move to the remove list */
list_move_tail(&mcast->list, &remove_list);
}
}
spin_unlock(&priv->lock);
netif_addr_unlock(dev);
[NET]: Add netif_tx_lock Various drivers use xmit_lock internally to synchronise with their transmission routines. They do so without setting xmit_lock_owner. This is fine as long as netpoll is not in use. With netpoll it is possible for deadlocks to occur if xmit_lock_owner isn't set. This is because if a printk occurs while xmit_lock is held and xmit_lock_owner is not set can cause netpoll to attempt to take xmit_lock recursively. While it is possible to resolve this by getting netpoll to use trylock, it is suboptimal because netpoll's sole objective is to maximise the chance of getting the printk out on the wire. So delaying or dropping the message is to be avoided as much as possible. So the only alternative is to always set xmit_lock_owner. The following patch does this by introducing the netif_tx_lock family of functions that take care of setting/unsetting xmit_lock_owner. I renamed xmit_lock to _xmit_lock to indicate that it should not be used directly. I didn't provide irq versions of the netif_tx_lock functions since xmit_lock is meant to be a BH-disabling lock. This is pretty much a straight text substitution except for a small bug fix in winbond. It currently uses netif_stop_queue/spin_unlock_wait to stop transmission. This is unsafe as an IRQ can potentially wake up the queue. So it is safer to use netif_tx_disable. The hamradio bits used spin_lock_irq but it is unnecessary as xmit_lock must never be taken in an IRQ handler. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-10 03:20:56 +08:00
local_irq_restore(flags);
ipoib_mcast_remove_list(&remove_list);
IB/ipoib: fix MCAST_FLAG_BUSY usage Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford <dledford@redhat.com>
2015-02-22 08:27:05 +08:00
/*
* Double check that we are still up
*/
if (test_bit(IPOIB_FLAG_OPER_UP, &priv->flags)) {
spin_lock_irqsave(&priv->lock, flags);
__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
spin_unlock_irqrestore(&priv->lock, flags);
}
}
#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG
struct ipoib_mcast_iter *ipoib_mcast_iter_init(struct net_device *dev)
{
struct ipoib_mcast_iter *iter;
iter = kmalloc(sizeof *iter, GFP_KERNEL);
if (!iter)
return NULL;
iter->dev = dev;
memset(iter->mgid.raw, 0, 16);
if (ipoib_mcast_iter_next(iter)) {
kfree(iter);
return NULL;
}
return iter;
}
int ipoib_mcast_iter_next(struct ipoib_mcast_iter *iter)
{
struct ipoib_dev_priv *priv = ipoib_priv(iter->dev);
struct rb_node *n;
struct ipoib_mcast *mcast;
int ret = 1;
spin_lock_irq(&priv->lock);
n = rb_first(&priv->multicast_tree);
while (n) {
mcast = rb_entry(n, struct ipoib_mcast, rb_node);
if (memcmp(iter->mgid.raw, mcast->mcmember.mgid.raw,
sizeof (union ib_gid)) < 0) {
iter->mgid = mcast->mcmember.mgid;
iter->created = mcast->created;
iter->queuelen = skb_queue_len(&mcast->pkt_queue);
iter->complete = !!mcast->ah;
iter->send_only = !!(mcast->flags & (1 << IPOIB_MCAST_FLAG_SENDONLY));
ret = 0;
break;
}
n = rb_next(n);
}
spin_unlock_irq(&priv->lock);
return ret;
}
void ipoib_mcast_iter_read(struct ipoib_mcast_iter *iter,
union ib_gid *mgid,
unsigned long *created,
unsigned int *queuelen,
unsigned int *complete,
unsigned int *send_only)
{
*mgid = iter->mgid;
*created = iter->created;
*queuelen = iter->queuelen;
*complete = iter->complete;
*send_only = iter->send_only;
}
#endif /* CONFIG_INFINIBAND_IPOIB_DEBUG */