There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Commit c7fd62bc69 ("stm class: Introduce framing protocol drivers")
forgot to tear down the link between an stm device and its protocol
driver when policy is removed. This leads to an invalid pointer reference
if one tries to write to an stm device after the policy has been removed
and the protocol driver module unloaded, leading to the below splat:
> BUG: unable to handle page fault for address: ffffffffc0737068
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 3d780f067 P4D 3d780f067 PUD 3d7811067 PMD 492781067 PTE 0
> Oops: 0000 [#1] SMP NOPTI
> CPU: 1 PID: 26122 Comm: cat Not tainted 5.4.0-rc5+ #1
> RIP: 0010:stm_output_free+0x40/0xc0 [stm_core]
> Call Trace:
> stm_char_release+0x3e/0x70 [stm_core]
> __fput+0xc6/0x260
> ____fput+0xe/0x10
> task_work_run+0x9d/0xc0
> exit_to_usermode_loop+0x103/0x110
> do_syscall_64+0x19d/0x1e0
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix this by tearing down the link from an stm device to its protocol
driver when the policy involving that driver is removed.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: c7fd62bc69 ("stm class: Introduce framing protocol drivers")
Reported-by: Ammy Yi <ammy.yi@intel.com>
Tested-by: Ammy Yi <ammy.yi@intel.com>
CC: stable@vger.kernel.org # v4.20+
Link: https://lore.kernel.org/r/20191114064201.43089-2-alexander.shishkin@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit c7fd62bc69 ("stm class: Introduce framing protocol drivers")
adds a bug into the error path of policy creation, that would do a
module_put() on a wrong module, if one tried to create a policy for
an stm device which already has a policy, using a different protocol.
IOW,
| mkdir /config/stp-policy/dummy_stm.0:p_basic.test
| mkdir /config/stp-policy/dummy_stm.0:p_sys-t.test # puts "p_basic"
| mkdir /config/stp-policy/dummy_stm.0:p_sys-t.test # "p_basic" -> -1
throws:
| general protection fault: 0000 [#1] SMP PTI
| CPU: 3 PID: 2887 Comm: mkdir
| RIP: 0010:module_put.part.31+0xe/0x90
| Call Trace:
| module_put+0x13/0x20
| stm_put_protocol+0x11/0x20 [stm_core]
| stp_policy_make+0xf1/0x210 [stm_core]
| ? __kmalloc+0x183/0x220
| ? configfs_mkdir+0x10d/0x4c0
| configfs_mkdir+0x169/0x4c0
| vfs_mkdir+0x108/0x1c0
| do_mkdirat+0xe8/0x110
| __x64_sys_mkdir+0x1b/0x20
| do_syscall_64+0x5a/0x140
| entry_SYSCALL_64_after_hwframe+0x44/0xa9
Correct this sad mistake by calling calling 'put' on the correct
reference, which happens to match another error path in the same
function, so we consolidate the two at the same time.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: c7fd62bc69 ("stm class: Introduce framing protocol drivers")
Reported-by: Ammy Yi <ammy.yi@intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of a local copy, use the memcat_p() helper to merge policy
node attributes.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that the default framing protocol is factored out into its own driver,
switch over to using the driver for writing data. To that end, make the
policy code require a valid protocol name (or absence thereof, which is
equivalent to "p_basic").
Also, to make transition easier, make stm class request "p_basic" module
at initialization time.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
At the moment, the stm class applies a certain STP framing pattern to
the data as it is written to the underlying STM device. In order to
allow different framing patterns (aka protocols), this patch introduces
the concept of STP protocol drivers, defines data structures and APIs
for the protocol drivers to use.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The current naming of stp-policy root type and group ops is confusing,
rename them for better readability.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, if no matching policy node can be found for a trace source,
we'll try to use "default" policy node, then, if that doesn't exist,
we'll pick the first node, in order of creation. If that also fails,
we'll allocate M/C range from the beginning of the device's M/C range.
This makes it difficult to know which node (if any) was used in any
particular case.
In order to make things more deterministic, the new order is as follows:
* if they supply ID string, use that and nothing else,
* if they are a task, use their task name (comm),
* use "default", if it exists,
* return failure, to let them know there is no suitable rule.
This should provide enough convenience with the "default" catch-all node,
while not leaving *everything* to chance. As a side effect, this relaxes
the requirement of using ioctl() for identification with the possibility of
using task names as policy nodes.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This adds SPDX GPL-2.0 header to to stm core files and removes the
GPLv2 boilerplate text.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Make config_item_type structures const as they are either passed to a
function having the argument as const or used inside a if statement or
stored in the const "ci_type" field of a config_item structure.
Done using Coccinelle.
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Readability: a postfix increment is used on a pointer which is not
used anywhere afterwards, which may send the reader looking through
the function one extra time. Drop the unnecessary increment.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
Master IDs are of unsigned int type, yet in the configfs policy code
we're validating user's input against INT_MAX. This is both pointless
and misleading as the real limits are imposed by the stm device's
[sw_start..sw_end] (which are also limited by the spec to be no larger
than 2^16-1).
Clean this up by getting rid of the redundant comparisons.
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
By convention, the name of the stm policy directory in configfs consists of
the device name to which it applies and the actual policy name, separated
by a dot. Now, some devices already have dots in their names that separate
name of the actual device from its instance identifier. Such devices will
result in two (or more, who can tell) dots in the policy directory name.
Existing policy code, however, will treat the first dot as the one that
separates device name from policy name, therefore failing the above case.
This patch makes the last dot in the directory name be the separator, thus
prohibiting dots from being used in policy names.
Suggested-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Right now, if stm device removal has to unbind from a policy (that is,
an stm device that has STP policy, gets removed), it will trigger a
nested lock on the stm device's policy mutex.
This patch fixes the problem by moving the locking from the policy
unbinding to policy removal (configfs path), where it's actually needed;
the other caller of the policy unbinding function already takes the
mutex around the call.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull SCSI target updates from Nicholas Bellinger:
"This series contains HCH's changes to absorb configfs attribute
->show() + ->store() function pointer usage from it's original
tree-wide consumers, into common configfs code.
It includes usb-gadget, target w/ drivers, netconsole and ocfs2
changes to realize the improved simplicity, that now renders the
original include/target/configfs_macros.h CPP magic for fabric drivers
and others, unnecessary and obsolete.
And with common code in place, new configfs attributes can be added
easier than ever before.
Note, there are further improvements in-flight from other folks for
v4.5 code in configfs land, plus number of target fixes for post -rc1
code"
In the meantime, a new user of the now-removed old configfs API came in
through the char/misc tree in commit 7bd1d4093c ("stm class: Introduce
an abstraction for System Trace Module devices").
This merge resolution comes from Alexander Shishkin, who updated his stm
class tracing abstraction to account for the removal of the old
show_attribute and store_attribute methods in commit 517982229f
("configfs: remove old API") from this pull. As Alexander says about
that patch:
"There's no need to keep an extra wrapper structure per item and the
awkward show_attribute/store_attribute item ops are no longer needed.
This patch converts policy code to the new api, all the while making
the code quite a bit smaller and easier on the eyes.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>"
That patch was folded into the merge so that the tree should be fully
bisectable.
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (23 commits)
configfs: remove old API
ocfs2/cluster: use per-attribute show and store methods
ocfs2/cluster: move locking into attribute store methods
netconsole: use per-attribute show and store methods
target: use per-attribute show and store methods
spear13xx_pcie_gadget: use per-attribute show and store methods
dlm: use per-attribute show and store methods
usb-gadget/f_serial: use per-attribute show and store methods
usb-gadget/f_phonet: use per-attribute show and store methods
usb-gadget/f_obex: use per-attribute show and store methods
usb-gadget/f_uac2: use per-attribute show and store methods
usb-gadget/f_uac1: use per-attribute show and store methods
usb-gadget/f_mass_storage: use per-attribute show and store methods
usb-gadget/f_sourcesink: use per-attribute show and store methods
usb-gadget/f_printer: use per-attribute show and store methods
usb-gadget/f_midi: use per-attribute show and store methods
usb-gadget/f_loopback: use per-attribute show and store methods
usb-gadget/ether: use per-attribute show and store methods
usb-gadget/f_acm: use per-attribute show and store methods
usb-gadget/f_hid: use per-attribute show and store methods
...
A System Trace Module (STM) is a device exporting data in System Trace
Protocol (STP) format as defined by MIPI STP standards. Examples of such
devices are Intel(R) Trace Hub and Coresight STM.
This abstraction provides a unified interface for software trace sources
to send their data over an STM device to a debug host. In order to do
that, such a trace source needs to be assigned a pair of master/channel
identifiers that all the data from this source will be tagged with. The
STP decoder on the debug host side will use these master/channel tags to
distinguish different trace streams from one another inside one STP
stream.
This abstraction provides a configfs-based policy management mechanism
for dynamic allocation of these master/channel pairs based on trace
source-supplied string identifier. It has the flexibility of being
defined at runtime and at the same time (provided that the policy
definition is aligned with the decoding end) consistency.
For userspace trace sources, this abstraction provides write()-based and
mmap()-based (if the underlying stm device allows this) output mechanism.
For kernel-side trace sources, we provide "stm_source" device class that
can be connected to an stm device at run time.
Cc: linux-api@vger.kernel.org
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
