Commit Graph

130 Commits

Author SHA1 Message Date
Vasily Averin
89163f93c6 ipc/util.c: sysvipc_find_ipc() should increase position index
If seq_file .next function does not change position index, read after
some lseek can generate unexpected output.

https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: NeilBrown <neilb@suse.com>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/b7a20945-e315-8bb0-21e6-3875c14a8494@virtuozzo.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-10 15:36:22 -07:00
Alexey Dobriyan
d919b33daf proc: faster open/read/close with "permanent" files
Now that "struct proc_ops" exist we can start putting there stuff which
could not fly with VFS "struct file_operations"...

Most of fs/proc/inode.c file is dedicated to make open/read/.../close
reliable in the event of disappearing /proc entries which usually happens
if module is getting removed.  Files like /proc/cpuinfo which never
disappear simply do not need such protection.

Save 2 atomic ops, 1 allocation, 1 free per open/read/close sequence for such
"permanent" files.

Enable "permanent" flag for

	/proc/cpuinfo
	/proc/kmsg
	/proc/modules
	/proc/slabinfo
	/proc/stat
	/proc/sysvipc/*
	/proc/swaps

More will come once I figure out foolproof way to prevent out module
authors from marking their stuff "permanent" for performance reasons
when it is not.

This should help with scalability: benchmark is "read /proc/cpuinfo R times
by N threads scattered over the system".

	N	R	t, s (before)	t, s (after)
	-----------------------------------------------------
	64	4096	1.582458	1.530502	-3.2%
	256	4096	6.371926	6.125168	-3.9%
	1024	4096	25.64888	24.47528	-4.6%

Benchmark source:

#include <chrono>
#include <iostream>
#include <thread>
#include <vector>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

const int NR_CPUS = sysconf(_SC_NPROCESSORS_ONLN);
int N;
const char *filename;
int R;

int xxx = 0;

int glue(int n)
{
	cpu_set_t m;
	CPU_ZERO(&m);
	CPU_SET(n, &m);
	return sched_setaffinity(0, sizeof(cpu_set_t), &m);
}

void f(int n)
{
	glue(n % NR_CPUS);

	while (*(volatile int *)&xxx == 0) {
	}

	for (int i = 0; i < R; i++) {
		int fd = open(filename, O_RDONLY);
		char buf[4096];
		ssize_t rv = read(fd, buf, sizeof(buf));
		asm volatile ("" :: "g" (rv));
		close(fd);
	}
}

int main(int argc, char *argv[])
{
	if (argc < 4) {
		std::cerr << "usage: " << argv[0] << ' ' << "N /proc/filename R
";
		return 1;
	}

	N = atoi(argv[1]);
	filename = argv[2];
	R = atoi(argv[3]);

	for (int i = 0; i < NR_CPUS; i++) {
		if (glue(i) == 0)
			break;
	}

	std::vector<std::thread> T;
	T.reserve(N);
	for (int i = 0; i < N; i++) {
		T.emplace_back(f, i);
	}

	auto t0 = std::chrono::system_clock::now();
	{
		*(volatile int *)&xxx = 1;
		for (auto& t: T) {
			t.join();
		}
	}
	auto t1 = std::chrono::system_clock::now();
	std::chrono::duration<double> dt = t1 - t0;
	std::cout << dt.count() << '
';

	return 0;
}

P.S.:
Explicit randomization marker is added because adding non-function pointer
will silently disable structure layout randomization.

[akpm@linux-foundation.org: coding style fixes]
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Joe Perches <joe@perches.com>
Link: http://lkml.kernel.org/r/20200222201539.GA22576@avx2
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:42 -07:00
Alexey Dobriyan
97a32539b9 proc: convert everything to "struct proc_ops"
The most notable change is DEFINE_SHOW_ATTRIBUTE macro split in
seq_file.h.

Conversion rule is:

	llseek		=> proc_lseek
	unlocked_ioctl	=> proc_ioctl

	xxx		=> proc_xxx

	delete ".owner = THIS_MODULE" line

[akpm@linux-foundation.org: fix drivers/isdn/capi/kcapi_proc.c]
[sfr@canb.auug.org.au: fix kernel/sched/psi.c]
  Link: http://lkml.kernel.org/r/20200122180545.36222f50@canb.auug.org.au
Link: http://lkml.kernel.org/r/20191225172546.GB13378@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-02-04 03:05:26 +00:00
Pankaj Bharadiya
c593642c8b treewide: Use sizeof_field() macro
Replace all the occurrences of FIELD_SIZEOF() with sizeof_field() except
at places where these are defined. Later patches will remove the unused
definition of FIELD_SIZEOF().

This patch is generated using following script:

EXCLUDE_FILES="include/linux/stddef.h|include/linux/kernel.h"

git grep -l -e "\bFIELD_SIZEOF\b" | while read file;
do

	if [[ "$file" =~ $EXCLUDE_FILES ]]; then
		continue
	fi
	sed -i  -e 's/\bFIELD_SIZEOF\b/sizeof_field/g' $file;
done

Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Link: https://lore.kernel.org/r/20190924105839.110713-3-pankaj.laxminarayan.bharadiya@intel.com
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: David Miller <davem@davemloft.net> # for net
2019-12-09 10:36:44 -08:00
Manfred Spraul
99db46ea29 ipc: do cyclic id allocation for the ipc object.
For ipcmni_extend mode, the sequence number space is only 7 bits.  So
the chance of id reuse is relatively high compared with the non-extended
mode.

To alleviate this id reuse problem, this patch enables cyclic allocation
for the index to the radix tree (idx).  The disadvantage is that this
can cause a slight slow-down of the fast path, as the radix tree could
be higher than necessary.

To limit the radix tree height, I have chosen the following limits:
 1) The cycling is done over in_use*1.5.
 2) At least, the cycling is done over
   "normal" ipcnmi mode: RADIX_TREE_MAP_SIZE elements
   "ipcmni_extended": 4096 elements

Result:
- for normal mode:
	No change for <= 42 active ipc elements. With more than 42
	active ipc elements, a 2nd level would be added to the radix
	tree.
	Without cyclic allocation, a 2nd level would be added only with
	more than 63 active elements.

- for extended mode:
	Cycling creates always at least a 2-level radix tree.
	With more than 2730 active objects, a 3rd level would be
	added, instead of > 4095 active objects until the 3rd level
	is added without cyclic allocation.

For a 2-level radix tree compared to a 1-level radix tree, I have
observed < 1% performance impact.

Notes:
1) Normal "x=semget();y=semget();" is unaffected: Then the idx
  is e.g. a and a+1, regardless if idr_alloc() or idr_alloc_cyclic()
  is used.

2) The -1% happens in a microbenchmark after this situation:
	x=semget();
	for(i=0;i<4000;i++) {t=semget();semctl(t,0,IPC_RMID);}
	y=semget();
	Now perform semget calls on x and y that do not sleep.

3) The worst-case reuse cycle time is unfortunately unaffected:
   If you have 2^24-1 ipc objects allocated, and get/remove the last
   possible element in a loop, then the id is reused after 128
   get/remove pairs.

Performance check:
A microbenchmark that performes no-op semop() randomly on two IDs,
with only these two IDs allocated.
The IDs were set using /proc/sys/kernel/sem_next_id.
The test was run 5 times, averages are shown.

1 & 2: Base (6.22 seconds for 10.000.000 semops)
1 & 40: -0.2%
1 & 3348: - 0.8%
1 & 27348: - 1.6%
1 & 15777204: - 3.2%

Or: ~12.6 cpu cycles per additional radix tree level.
The cpu is an Intel I3-5010U. ~1300 cpu cycles/syscall is slower
than what I remember (spectre impact?).

V2 of the patch:
- use "min" and "max"
- use RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE instead of
	(2<<12).

[akpm@linux-foundation.org: fix max() warning]
Link: http://lkml.kernel.org/r/20190329204930.21620-3-longman@redhat.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Waiman Long <longman@redhat.com>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 19:52:52 -07:00
Manfred Spraul
3278a2c20c ipc: conserve sequence numbers in ipcmni_extend mode
Rewrite, based on the patch from Waiman Long:

The mixing in of a sequence number into the IPC IDs is probably to avoid
ID reuse in userspace as much as possible.  With ipcmni_extend mode, the
number of usable sequence numbers is greatly reduced leading to higher
chance of ID reuse.

To address this issue, we need to conserve the sequence number space as
much as possible.  Right now, the sequence number is incremented for
every new ID created.  In reality, we only need to increment the
sequence number when new allocated ID is not greater than the last one
allocated.  It is in such case that the new ID may collide with an
existing one.  This is being done irrespective of the ipcmni mode.

In order to avoid any races, the index is first allocated and then the
pointer is replaced.

Changes compared to the initial patch:
 - Handle failures from idr_alloc().
 - Avoid that concurrent operations can see the wrong sequence number.
   (This is achieved by using idr_replace()).
 - IPCMNI_SEQ_SHIFT is not a constant, thus renamed to
   ipcmni_seq_shift().
 - IPCMNI_SEQ_MAX is not a constant, thus renamed to ipcmni_seq_max().

Link: http://lkml.kernel.org/r/20190329204930.21620-2-longman@redhat.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 19:52:52 -07:00
Waiman Long
5ac893b8cb ipc: allow boot time extension of IPCMNI from 32k to 16M
The maximum number of unique System V IPC identifiers was limited to
32k.  That limit should be big enough for most use cases.

However, there are some users out there requesting for more, especially
those that are migrating from Solaris which uses 24 bits for unique
identifiers.  To satisfy the need of those users, a new boot time kernel
option "ipcmni_extend" is added to extend the IPCMNI value to 16M.  This
is a 512X increase which should be big enough for users out there that
need a large number of unique IPC identifier.

The use of this new option will change the pattern of the IPC
identifiers returned by functions like shmget(2).  An application that
depends on such pattern may not work properly.  So it should only be
used if the users really need more than 32k of unique IPC numbers.

This new option does have the side effect of reducing the maximum number
of unique sequence numbers from 64k down to 128.  So it is a trade-off.

The computation of a new IPC id is not done in the performance critical
path.  So a little bit of additional overhead shouldn't have any real
performance impact.

Link: http://lkml.kernel.org/r/20190329204930.21620-1-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 19:52:52 -07:00
NeilBrown
8f0db01800 rhashtable: use bit_spin_locks to protect hash bucket.
This patch changes rhashtables to use a bit_spin_lock on BIT(1) of the
bucket pointer to lock the hash chain for that bucket.

The benefits of a bit spin_lock are:
 - no need to allocate a separate array of locks.
 - no need to have a configuration option to guide the
   choice of the size of this array
 - locking cost is often a single test-and-set in a cache line
   that will have to be loaded anyway.  When inserting at, or removing
   from, the head of the chain, the unlock is free - writing the new
   address in the bucket head implicitly clears the lock bit.
   For __rhashtable_insert_fast() we ensure this always happens
   when adding a new key.
 - even when lockings costs 2 updates (lock and unlock), they are
   in a cacheline that needs to be read anyway.

The cost of using a bit spin_lock is a little bit of code complexity,
which I think is quite manageable.

Bit spin_locks are sometimes inappropriate because they are not fair -
if multiple CPUs repeatedly contend of the same lock, one CPU can
easily be starved.  This is not a credible situation with rhashtable.
Multiple CPUs may want to repeatedly add or remove objects, but they
will typically do so at different buckets, so they will attempt to
acquire different locks.

As we have more bit-locks than we previously had spinlocks (by at
least a factor of two) we can expect slightly less contention to
go with the slightly better cache behavior and reduced memory
consumption.

To enhance type checking, a new struct is introduced to represent the
  pointer plus lock-bit
that is stored in the bucket-table.  This is "struct rhash_lock_head"
and is empty.  A pointer to this needs to be cast to either an
unsigned lock, or a "struct rhash_head *" to be useful.
Variables of this type are most often called "bkt".

Previously "pprev" would sometimes point to a bucket, and sometimes a
->next pointer in an rhash_head.  As these are now different types,
pprev is NULL when it would have pointed to the bucket. In that case,
'blk' is used, together with correct locking protocol.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-07 19:12:12 -07:00
Manfred Spraul
2a9d648100 ipc/util.c: update return value of ipc_getref from int to bool
ipc_getref has still a return value of type "int", matching the atomic_t
interface of atomic_inc_not_zero()/atomic_add_unless().

ipc_getref now uses refcount_inc_not_zero, which has a return value of
type "bool".

Therefore, update the return code to avoid implicit conversions.

Link: http://lkml.kernel.org/r/20180712185241.4017-13-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:52 -07:00
Manfred Spraul
27c331a174 ipc/util.c: further variable name cleanups
The varable names got a mess, thus standardize them again:

id: user space id. Called semid, shmid, msgid if the type is known.
    Most functions use "id" already.
idx: "index" for the idr lookup
    Right now, some functions use lid, ipc_addid() already uses idx as
    the variable name.
seq: sequence number, to avoid quick collisions of the user space id
key: user space key, used for the rhash tree

Link: http://lkml.kernel.org/r/20180712185241.4017-12-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:52 -07:00
Davidlohr Bueso
eae04d25a7 ipc: simplify ipc initialization
Now that we know that rhashtable_init() will not fail, we can get rid of a
lot of the unnecessary cleanup paths when the call errored out.

[manfred@colorfullife.com: variable name added to util.h to resolve checkpatch warning]
Link: http://lkml.kernel.org/r/20180712185241.4017-11-manfred@colorfullife.com
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:52 -07:00
Davidlohr Bueso
dc2c8c84de ipc: get rid of ids->tables_initialized hack
In sysvipc we have an ids->tables_initialized regarding the rhashtable,
introduced in 0cfb6aee70 ("ipc: optimize semget/shmget/msgget for lots
of keys")

It's there, specifically, to prevent nil pointer dereferences, from using
an uninitialized api.  Considering how rhashtable_init() can fail
(probably due to ENOMEM, if anything), this made the overall ipc
initialization capable of failure as well.  That alone is ugly, but fine,
however I've spotted a few issues regarding the semantics of
tables_initialized (however unlikely they may be):

- There is inconsistency in what we return to userspace: ipc_addid()
  returns ENOSPC which is certainly _wrong_, while ipc_obtain_object_idr()
  returns EINVAL.

- After we started using rhashtables, ipc_findkey() can return nil upon
  !tables_initialized, but the caller expects nil for when the ipc
  structure isn't found, and can therefore call into ipcget() callbacks.

Now that rhashtable initialization cannot fail, we can properly get rid of
the hack altogether.

[manfred@colorfullife.com: commit id extended to 12 digits]
Link: http://lkml.kernel.org/r/20180712185241.4017-10-manfred@colorfullife.com
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:52 -07:00
Davidlohr Bueso
82061c57ce ipc: drop ipc_lock()
ipc/util.c contains multiple functions to get the ipc object pointer given
an id number.

There are two sets of function: One set verifies the sequence counter part
of the id number, other functions do not check the sequence counter.

The standard for function names in ipc/util.c is
- ..._check() functions verify the sequence counter
- ..._idr() functions do not verify the sequence counter

ipc_lock() is an exception: It does not verify the sequence counter value,
but this is not obvious from the function name.

Furthermore, shm.c is the only user of this helper.  Thus, we can simply
move the logic into shm_lock() and get rid of the function altogether.

[manfred@colorfullife.com: most of changelog]
Link: http://lkml.kernel.org/r/20180712185241.4017-7-manfred@colorfullife.com
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:52 -07:00
Manfred Spraul
2e5ceb452c ipc/util.c: correct comment in ipc_obtain_object_check
The comment that explains ipc_obtain_object_check is wrong: The function
checks the sequence number, not the reference counter.

Note that checking the reference counter would be meaningless: The
reference counter is decreased without holding any locks, thus an object
with kern_ipc_perm.deleted=true may disappear at the end of the next rcu
grace period.

Link: http://lkml.kernel.org/r/20180712185241.4017-6-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:52 -07:00
Manfred Spraul
4241c1a304 ipc: rename ipcctl_pre_down_nolock()
Both the comment and the name of ipcctl_pre_down_nolock() are misleading:
The function must be called while holdling the rw semaphore.

Therefore the patch renames the function to ipcctl_obtain_check(): This
name matches the other names used in util.c:

- "obtain" function look up a pointer in the idr, without
  acquiring the object lock.
- The caller is responsible for locking.
- _check means that the sequence number is checked.

Link: http://lkml.kernel.org/r/20180712185241.4017-5-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:51 -07:00
Manfred Spraul
39cfffd774 ipc/util.c: use ipc_rcu_putref() for failues in ipc_addid()
ipc_addid() is impossible to use:
- for certain failures, the caller must not use ipc_rcu_putref(),
  because the reference counter is not yet initialized.
- for other failures, the caller must use ipc_rcu_putref(),
  because parallel operations could be ongoing already.

The patch cleans that up, by initializing the refcount early, and by
modifying all callers.

The issues is related to the finding of
syzbot+2827ef6b3385deb07eaf@syzkaller.appspotmail.com: syzbot found an
issue with reading kern_ipc_perm.seq, here both read and write to already
released memory could happen.

Link: http://lkml.kernel.org/r/20180712185241.4017-4-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:51 -07:00
Manfred Spraul
e2652ae6bd ipc: reorganize initialization of kern_ipc_perm.seq
ipc_addid() initializes kern_ipc_perm.seq after having called idr_alloc()
(within ipc_idr_alloc()).

Thus a parallel semop() or msgrcv() that uses ipc_obtain_object_check()
may see an uninitialized value.

The patch moves the initialization of kern_ipc_perm.seq before the calls
of idr_alloc().

Notes:
1) This patch has a user space visible side effect:
If /proc/sys/kernel/*_next_id is used (i.e.: checkpoint/restore) and
if semget()/msgget()/shmget() fails in the final step of adding the id
to the rhash tree, then .._next_id is cleared. Before the patch, is
remained unmodified.

There is no change of the behavior after a successful ..get() call: It
always clears .._next_id, there is no impact to non checkpoint/restore
code as that code does not use .._next_id.

2) The patch correctly documents that after a call to ipc_idr_alloc(),
the full tear-down sequence must be used. The callers of ipc_addid()
do not fullfill that, i.e. more bugfixes are required.

The patch is a squash of a patch from Dmitry and my own changes.

Link: http://lkml.kernel.org/r/20180712185241.4017-3-manfred@colorfullife.com
Reported-by: syzbot+2827ef6b3385deb07eaf@syzkaller.appspotmail.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:51 -07:00
NeilBrown
0eb71a9da5 rhashtable: split rhashtable.h
Due to the use of rhashtables in net namespaces,
rhashtable.h is included in lots of the kernel,
so a small changes can required a large recompilation.
This makes development painful.

This patch splits out rhashtable-types.h which just includes
the major type declarations, and does not include (non-trivial)
inline code.  rhashtable.h is no longer included by anything
in the include/ directory.
Common include files only include rhashtable-types.h so a large
recompilation is only triggered when that changes.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-22 13:43:27 +09:00
Alexey Dobriyan
e74a0effff proc: move /proc/sysvipc creation to where it belongs
Move the proc_mkdir() call within the sysvipc subsystem such that we
avoid polluting proc_root_init() with petty cpp.

[dave@stgolabs.net: contributed changelog]
Link: http://lkml.kernel.org/r/20180216161732.GA10297@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:33 -07:00
Eric W. Biederman
03f1fc0918 ipc/util: Helpers for making the sysvipc operations pid namespace aware
Capture the pid namespace when /proc/sysvipc/msg /proc/sysvipc/shm
and /proc/sysvipc/sem are opened, and make it available through
the new helper ipc_seq_pid_ns.

This makes it possible to report the pids in these files in the
pid namespace of the opener of the files.

Implement ipc_update_pid.  A simple impline helper that will only update
a struct pid pointer if the new value does not equal the old value.  This
removes the need for wordy code sequences like:

	old = object->pid;
	object->pid = new;
	put_pid(old);

and

	old = object->pid;
	if (old != new) {
		object->pid = new;
		put_pid(old);
	}

Allowing the following to be written instead:

	ipc_update_pid(&object->pid, new);

Which is easier to read and ensures that the pid reference count is
not touched the old and the new values are the same.  Not touching
the reference count in this case is important to help avoid issues
like af_unix experienced, where multiple threads of the same
process managed to bounce the struct pid between cpu cache lines,
but updating the pids reference count.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-24 11:25:37 -05:00
Philippe Mikoyan
87ad4b0d85 ipc: fix ipc data structures inconsistency
As described in the title, this patch fixes <ipc>id_ds inconsistency when
<ipc>ctl_stat executes concurrently with some ds-changing function, e.g.
shmat, msgsnd or whatever.

For instance, if shmctl(IPC_STAT) is running concurrently
with shmat, following data structure can be returned:
{... shm_lpid = 0, shm_nattch = 1, ...}

Link: http://lkml.kernel.org/r/20171202153456.6514-1-philippe.mikoyan@skat.systems
Signed-off-by: Philippe Mikoyan <philippe.mikoyan@skat.systems>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06 18:32:46 -08:00
Davidlohr Bueso
15df03c879 sysvipc: make get_maxid O(1) again
For a custom microbenchmark on a 3.30GHz Xeon SandyBridge, which calls
IPC_STAT over and over, it was calculated that, on avg the cost of
ipc_get_maxid() for increasing amounts of keys was:

 10 keys: ~900 cycles
 100 keys: ~15000 cycles
 1000 keys: ~150000 cycles
 10000 keys: ~2100000 cycles

This is unsurprising as maxid is currently O(n).

By having the max_id available in O(1) we save all those cycles for each
semctl(_STAT) command, the idr_find can be expensive -- which some real
(customer) workloads actually poll on.

Note that this used to be the case, until commit 7ca7e564e0 ("ipc:
store ipcs into IDRs").  The cost is the extra idr_find when doing
RMIDs, but we simply go backwards, and should not take too many
iterations to find the new value.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170831172049.14576-5-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-17 16:10:04 -08:00
Davidlohr Bueso
ebf66799ac sysvipc: properly name ipc_addid() limit parameter
This is better understood as a limit, instead of size; exactly like the
function comment indicates.  Rename it.

Link: http://lkml.kernel.org/r/20170831172049.14576-4-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-17 16:10:04 -08:00
Davidlohr Bueso
b8fd998384 sysvipc: unteach ids->next_id for !CHECKPOINT_RESTORE
Patch series "sysvipc: ipc-key management improvements".

Here are a few improvements I spotted while eyeballing Guillaume's
rhashtable implementation for ipc keys.  The first and fourth patches
are the interesting ones, the middle two are trivial.

This patch (of 4):

The next_id object-allocation functionality was introduced in commit
03f5956680 ("ipc: add sysctl to specify desired next object id").

Given that these new entries are _only_ exported under the
CONFIG_CHECKPOINT_RESTORE option, there is no point for the common case
to even know about ->next_id.  As such rewrite ipc_buildid() such that
it can do away with the field as well as unnecessary branches when
adding a new identifier.  The end result also better differentiates both
cases, so the code ends up being cleaner; albeit the small duplications
regarding the default case.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170831172049.14576-2-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-17 16:10:04 -08:00
Greg Kroah-Hartman
b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Guillaume Knispel
0cfb6aee70 ipc: optimize semget/shmget/msgget for lots of keys
ipc_findkey() used to scan all objects to look for the wanted key.  This
is slow when using a high number of keys.  This change adds an rhashtable
of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n).

This change gives a 865% improvement of benchmark reaim.jobs_per_min on a
56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1]

Other (more micro) benchmark results, by the author: On an i5 laptop, the
following loop executed right after a reboot took, without and with this
change:

    for (int i = 0, k=0x424242; i < KEYS; ++i)
        semget(k++, 1, IPC_CREAT | 0600);

                 total       total          max single  max single
   KEYS        without        with        call without   call with

      1            3.5         4.9   µs            3.5         4.9
     10            7.6         8.6   µs            3.7         4.7
     32           16.2        15.9   µs            4.3         5.3
    100           72.9        41.8   µs            3.7         4.7
   1000        5,630.0       502.0   µs             *           *
  10000    1,340,000.0     7,240.0   µs             *           *
  31900   17,600,000.0    22,200.0   µs             *           *

 *: unreliable measure: high variance

The duration for a lookup-only usage was obtained by the same loop once
the keys are present:

                 total       total          max single  max single
   KEYS        without        with        call without   call with

      1            2.1         2.5   µs            2.1         2.5
     10            4.5         4.8   µs            2.2         2.3
     32           13.0        10.8   µs            2.3         2.8
    100           82.9        25.1   µs             *          2.3
   1000        5,780.0       217.0   µs             *           *
  10000    1,470,000.0     2,520.0   µs             *           *
  31900   17,400,000.0     7,810.0   µs             *           *

Finally, executing each semget() in a new process gave, when still
summing only the durations of these syscalls:

creation:
                 total       total
   KEYS        without        with

      1            3.7         5.0   µs
     10           32.9        36.7   µs
     32          125.0       109.0   µs
    100          523.0       353.0   µs
   1000       20,300.0     3,280.0   µs
  10000    2,470,000.0    46,700.0   µs
  31900   27,800,000.0   219,000.0   µs

lookup-only:
                 total       total
   KEYS        without        with

      1            2.5         2.7   µs
     10           25.4        24.4   µs
     32          106.0        72.6   µs
    100          591.0       352.0   µs
   1000       22,400.0     2,250.0   µs
  10000    2,510,000.0    25,700.0   µs
  31900   28,200,000.0   115,000.0   µs

[1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop

Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix
Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com>
Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com>
Cc: Marc Pardo <marc.pardo@supersonicimagine.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:51 -07:00
Elena Reshetova
9405c03ee7 ipc: convert kern_ipc_perm.refcount from atomic_t to refcount_t
refcount_t type and corresponding API should be used instead of atomic_t
when the variable is used as a reference counter.  This allows to avoid
accidental refcounter overflows that might lead to use-after-free
situations.

Link: http://lkml.kernel.org/r/1499417992-3238-4-git-send-email-elena.reshetova@intel.com
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: <arozansk@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:51 -07:00
Kees Cook
3d3653f973 ipc: move atomic_set() to where it is needed
Only after ipc_addid() has succeeded will refcounting be used, so move
initialization into ipc_addid() and remove from open-coded *_alloc()
routines.

Link: http://lkml.kernel.org/r/20170525185107.12869-17-manfred@colorfullife.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:02 -07:00
Kees Cook
c3f6fb6fe4 ipc/util: drop ipc_rcu_alloc()
No callers remain for ipc_rcu_alloc().  Drop the function.

[manfred@colorfullife.com: Rediff because the memset was temporarily inside ipc_rcu_free()]
Link: http://lkml.kernel.org/r/20170525185107.12869-13-manfred@colorfullife.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:02 -07:00
Kees Cook
5ccc8fb54f ipc/util: drop ipc_rcu_free()
There are no more callers of ipc_rcu_free(), so remove it.

Link: http://lkml.kernel.org/r/20170525185107.12869-9-manfred@colorfullife.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:01 -07:00
Kees Cook
f8dbe8d290 ipc: drop non-RCU allocation
The only users of ipc_alloc() were ipc_rcu_alloc() and the on-heap
sem_io fall-back memory.  Better to just open-code these to make things
easier to read.

[manfred@colorfullife.com: Rediff due to inclusion of memset() into ipc_rcu_alloc()]
Link: http://lkml.kernel.org/r/20170525185107.12869-5-manfred@colorfullife.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:01 -07:00
Manfred Spraul
dba4cdd39e ipc: merge ipc_rcu and kern_ipc_perm
ipc has two management structures that exist for every id:
 - struct kern_ipc_perm, it contains e.g. the permissions.
 - struct ipc_rcu, it contains the rcu head for rcu handling and the
   refcount.

The patch merges both structures.

As a bonus, we may save one cacheline, because both structures are
cacheline aligned.  In addition, it reduces the number of casts, instead
most codepaths can use container_of.

To simplify code, the ipc_rcu_alloc initializes the allocation to 0.

[manfred@colorfullife.com: really include the memset() into ipc_alloc_rcu()]
  Link: http://lkml.kernel.org/r/564f8612-0601-b267-514f-a9f650ec9b32@colorfullife.com
Link: http://lkml.kernel.org/r/20170525185107.12869-3-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:01 -07:00
Michal Hocko
a7c3e901a4 mm: introduce kv[mz]alloc helpers
Patch series "kvmalloc", v5.

There are many open coded kmalloc with vmalloc fallback instances in the
tree.  Most of them are not careful enough or simply do not care about
the underlying semantic of the kmalloc/page allocator which means that
a) some vmalloc fallbacks are basically unreachable because the kmalloc
part will keep retrying until it succeeds b) the page allocator can
invoke a really disruptive steps like the OOM killer to move forward
which doesn't sound appropriate when we consider that the vmalloc
fallback is available.

As it can be seen implementing kvmalloc requires quite an intimate
knowledge if the page allocator and the memory reclaim internals which
strongly suggests that a helper should be implemented in the memory
subsystem proper.

Most callers, I could find, have been converted to use the helper
instead.  This is patch 6.  There are some more relying on __GFP_REPEAT
in the networking stack which I have converted as well and Eric Dumazet
was not opposed [2] to convert them as well.

[1] http://lkml.kernel.org/r/20170130094940.13546-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/1485273626.16328.301.camel@edumazet-glaptop3.roam.corp.google.com

This patch (of 9):

Using kmalloc with the vmalloc fallback for larger allocations is a
common pattern in the kernel code.  Yet we do not have any common helper
for that and so users have invented their own helpers.  Some of them are
really creative when doing so.  Let's just add kv[mz]alloc and make sure
it is implemented properly.  This implementation makes sure to not make
a large memory pressure for > PAGE_SZE requests (__GFP_NORETRY) and also
to not warn about allocation failures.  This also rules out the OOM
killer as the vmalloc is a more approapriate fallback than a disruptive
user visible action.

This patch also changes some existing users and removes helpers which
are specific for them.  In some cases this is not possible (e.g.
ext4_kvmalloc, libcfs_kvzalloc) because those seems to be broken and
require GFP_NO{FS,IO} context which is not vmalloc compatible in general
(note that the page table allocation is GFP_KERNEL).  Those need to be
fixed separately.

While we are at it, document that __vmalloc{_node} about unsupported gfp
mask because there seems to be a lot of confusion out there.
kvmalloc_node will warn about GFP_KERNEL incompatible (which are not
superset) flags to catch new abusers.  Existing ones would have to die
slowly.

[sfr@canb.auug.org.au: f2fs fixup]
  Link: http://lkml.kernel.org/r/20170320163735.332e64b7@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170306103032.2540-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>	[ext4 part]
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-08 17:15:12 -07:00
mchehab@s-opensource.com
0e056eb553 kernel-api.rst: fix a series of errors when parsing C files
./lib/string.c:134: WARNING: Inline emphasis start-string without end-string.
./mm/filemap.c:522: WARNING: Inline interpreted text or phrase reference start-string without end-string.
./mm/filemap.c:1283: ERROR: Unexpected indentation.
./mm/filemap.c:3003: WARNING: Inline interpreted text or phrase reference start-string without end-string.
./mm/vmalloc.c:1544: WARNING: Inline emphasis start-string without end-string.
./mm/page_alloc.c:4245: ERROR: Unexpected indentation.
./ipc/util.c:676: ERROR: Unexpected indentation.
./drivers/pci/irq.c:35: WARNING: Block quote ends without a blank line; unexpected unindent.
./security/security.c:109: ERROR: Unexpected indentation.
./security/security.c:110: WARNING: Definition list ends without a blank line; unexpected unindent.
./block/genhd.c:275: WARNING: Inline strong start-string without end-string.
./block/genhd.c:283: WARNING: Inline strong start-string without end-string.
./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
./ipc/util.c:477: ERROR: Unknown target name: "s".

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-04-02 14:31:49 -06:00
Tetsuo Handa
1d5cfdb076 tree wide: use kvfree() than conditional kfree()/vfree()
There are many locations that do

  if (memory_was_allocated_by_vmalloc)
    vfree(ptr);
  else
    kfree(ptr);

but kvfree() can handle both kmalloc()ed memory and vmalloc()ed memory
using is_vmalloc_addr().  Unless callers have special reasons, we can
replace this branch with kvfree().  Please check and reply if you found
problems.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Jan Kara <jack@suse.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: David Rientjes <rientjes@google.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Boris Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-22 17:02:18 -08:00
Linus Torvalds
b9a5322779 Initialize msg/shm IPC objects before doing ipc_addid()
As reported by Dmitry Vyukov, we really shouldn't do ipc_addid() before
having initialized the IPC object state.  Yes, we initialize the IPC
object in a locked state, but with all the lockless RCU lookup work,
that IPC object lock no longer means that the state cannot be seen.

We already did this for the IPC semaphore code (see commit e8577d1f03:
"ipc/sem.c: fully initialize sem_array before making it visible") but we
clearly forgot about msg and shm.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-30 12:48:40 -04:00
Davidlohr Bueso
6157dbbfbf ipc,sysv: return -EINVAL upon incorrect id/seqnum
In ipc_obtain_object_check we return -EIDRM when a bogus sequence number
is detected via ipc_checkid, while the ipc manpages state the following
return codes for such errors:

   EIDRM  <ID> points to a removed identifier.
   EINVAL Invalid <ID> value, or unaligned, etc.

EIDRM should only be returned upon a RMID call (->deleted check), and thus
return EINVAL for wrong seq.  This difference in semantics has also caused
real bugs, ie: https://bugzilla.redhat.com/show_bug.cgi?id=246509

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30 19:44:59 -07:00
Davidlohr Bueso
f8b5918495 ipc,sysv: make return -EIDRM when racing with RMID consistent
The ipc_lock helper is used by all forms of sysv ipc to acquire the ipc
object's spinlock.  Upon error (bogus identifier), we always return
-EINVAL, whether the problem be in the idr path or because we raced with a
task performing RMID.  For the later, however, all ipc related manpages,
state the that for:

       EIDRM  <ID> points to a removed identifier.

And return:

       EINVAL Invalid <ID> value, or unaligned, etc.

Which (EINVAL) should only return once the ipc resource is deleted.  For
all types of ipc this is done immediately upon a RMID command.  However,
shared memory behaves slightly different as it can merely mark a segment
for deletion, and delay the actual freeing until there are no more active
consumers.  Per shmctl(IPC_RMID) manpage:

""
Mark  the  segment to be destroyed.  The segment will only actually
be destroyed after the last process detaches it (i.e., when the
shm_nattch member of the associated structure shmid_ds is zero).
""

Unlike ipc_lock, paths that behave "correctly", at least per the manpage,
involve controlling the ipc resource via *ctl(), doing the exact same
validity check as ipc_lock after right acquiring the spinlock:

	if (!ipc_valid_object()) {
		err = -EIDRM;
		goto out_unlock;
	}

Thus make ipc_lock consistent with the rest of ipc code and return -EIDRM
in ipc_lock when !ipc_valid_object().

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30 19:44:59 -07:00
Davidlohr Bueso
55b7ae5016 ipc: rename ipc_obtain_object
...  to ipc_obtain_object_idr, which is more meaningful and makes the code
slightly easier to follow.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30 19:44:58 -07:00
Pekka Enberg
c859aa8311 ipc/util.c: use kvfree() in ipc_rcu_free()
Use kvfree() instead of open-coding it.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30 19:44:58 -07:00
Joe Perches
7f032d6ef6 ipc: remove use of seq_printf return value
The seq_printf return value, because it's frequently misused,
will eventually be converted to void.

See: commit 1f33c41c03 ("seq_file: Rename seq_overflow() to
     seq_has_overflowed() and make public")

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15 16:35:24 -07:00
Manfred Spraul
0050ee059f ipc/msg: increase MSGMNI, remove scaling
SysV can be abused to allocate locked kernel memory.  For most systems, a
small limit doesn't make sense, see the discussion with regards to SHMMAX.

Therefore: increase MSGMNI to the maximum supported.

And: If we ignore the risk of locking too much memory, then an automatic
scaling of MSGMNI doesn't make sense.  Therefore the logic can be removed.

The code preserves auto_msgmni to avoid breaking any user space applications
that expect that the value exists.

Notes:
1) If an administrator must limit the memory allocations, then he can set
MSGMNI as necessary.

Or he can disable sysv entirely (as e.g. done by Android).

2) MSGMAX and MSGMNB are intentionally not increased, as these values are used
to control latency vs. throughput:
If MSGMNB is large, then msgsnd() just returns and more messages can be queued
before a task switch to a task that calls msgrcv() is forced.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-13 12:42:52 -08:00
Rob Jones
d66a0520cb ipc/util.c: use __seq_open_private() instead of seq_open()
Using __seq_open_private() removes boilerplate code from
sysvipc_proc_open().

The resultant code is shorter and easier to follow.

However, please note that __seq_open_private() call kzalloc() rather than
kmalloc() which may affect timing due to the memory initialisation
overhead.

Signed-off-by: Rob Jones <rob.jones@codethink.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-14 02:18:23 +02:00
Masanari Iida
da3dae54e4 Documentation: Docbook: Fix generated DocBook/kernel-api.xml
This patch fix spelling typo found in DocBook/kernel-api.xml.
It is because the file is generated from the source comments,
I have to fix the comments in source codes.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2014-09-09 10:34:56 +02:00
Paul McQuade
46c0a8ca3e ipc, kernel: clear whitespace
trailing whitespace

Signed-off-by: Paul McQuade <paulmcquad@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 16:08:14 -07:00
Mathias Krause
eb66ec44f8 ipc: constify ipc_ops
There is no need to recreate the very same ipc_ops structure on every
kernel entry for msgget/semget/shmget.  Just declare it static and be
done with it.  While at it, constify it as we don't modify the structure
at runtime.

Found in the PaX patch, written by the PaX Team.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 16:08:14 -07:00
Davidlohr Bueso
6d08a2567c ipc: use device_initcall
... since __initcall is now deprecated.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:36:11 -07:00
Davidlohr Bueso
daf948c7d1 ipc: delete seq_max field in struct ipc_ids
This field is only used to reset the ids seq number if it exceeds the
smaller of INT_MAX/SEQ_MULTIPLIER and USHRT_MAX, and can therefore be
moved out of the structure and into its own macro.  Since each
ipc_namespace contains a table of 3 pointers to struct ipc_ids we can
save space in instruction text:

   text    data     bss     dec     hex filename
  56232    2348      24   58604    e4ec ipc/built-in.o
  56216    2348      24   58588    e4dc ipc/built-in.o-after

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Jonathan Gonzalez <jgonzalez@linets.cl>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-27 21:02:40 -08:00
Davidlohr Bueso
8dc5cd04f9 ipc: simplify sysvipc_proc_open() return
Get rid of silly/useless label jumping.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-27 21:02:40 -08:00
Davidlohr Bueso
95d4eb2822 ipc: remove useless return statement
Only found in ipc_rmid().

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-27 21:02:40 -08:00