Commit graph

85 commits

Author SHA1 Message Date
Arnd Bergmann
b0d175781a y2038: ipc: Enable COMPAT_32BIT_TIME
Three ipc syscalls (mq_timedsend, mq_timedreceive and and semtimedop)
take a timespec argument. After we move 32-bit architectures over to
useing 64-bit time_t based syscalls, we need seperate entry points for
the old 32-bit based interfaces.

This changes the #ifdef guards for the existing 32-bit compat syscalls
to check for CONFIG_COMPAT_32BIT_TIME instead, which will then be
enabled on all existing 32-bit architectures.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2018-04-20 16:20:27 +02:00
Arnd Bergmann
21fc538d81 y2038: ipc: Use __kernel_timespec
This is a preparatation for changing over __kernel_timespec to 64-bit
times, which involves assigning new system call numbers for mq_timedsend(),
mq_timedreceive() and semtimedop() for compatibility with future y2038
proof user space.

The existing ABIs will remain available through compat code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2018-04-20 16:20:24 +02:00
Linus Torvalds
17dec0a949 Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull namespace updates from Eric Biederman:
 "There was a lot of work this cycle fixing bugs that were discovered
  after the merge window and getting everything ready where we can
  reasonably support fully unprivileged fuse. The bug fixes you already
  have and much of the unprivileged fuse work is coming in via other
  trees.

  Still left for fully unprivileged fuse is figuring out how to cleanly
  handle .set_acl and .get_acl in the legacy case, and properly handling
  of evm xattrs on unprivileged mounts.

  Included in the tree is a cleanup from Alexely that replaced a linked
  list with a statically allocated fix sized array for the pid caches,
  which simplifies and speeds things up.

  Then there is are some cleanups and fixes for the ipc namespace. The
  motivation was that in reviewing other code it was discovered that
  access ipc objects from different pid namespaces recorded pids in such
  a way that when asked the wrong pids were returned. In the worst case
  there has been a measured 30% performance impact for sysvipc
  semaphores. Other test cases showed no measurable performance impact.
  Manfred Spraul and Davidlohr Bueso who tend to work on sysvipc
  performance both gave the nod that this is good enough.

  Casey Schaufler and James Morris have given their approval to the LSM
  side of the changes.

  I simplified the types and the code dealing with sysvipc to pass just
  kern_ipc_perm for all three types of ipc. Which reduced the header
  dependencies throughout the kernel and simplified the lsm code.

  Which let me work on the pid fixes without having to worry about
  trivial changes causing complete kernel recompiles"

* 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  ipc/shm: Fix pid freeing.
  ipc/shm: fix up for struct file no longer being available in shm.h
  ipc/smack: Tidy up from the change in type of the ipc security hooks
  ipc: Directly call the security hook in ipc_ops.associate
  ipc/sem: Fix semctl(..., GETPID, ...) between pid namespaces
  ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces
  ipc/shm: Fix shmctl(..., IPC_STAT, ...) between pid namespaces.
  ipc/util: Helpers for making the sysvipc operations pid namespace aware
  ipc: Move IPCMNI from include/ipc.h into ipc/util.h
  msg: Move struct msg_queue into ipc/msg.c
  shm: Move struct shmid_kernel into ipc/shm.c
  sem: Move struct sem and struct sem_array into ipc/sem.c
  msg/security: Pass kern_ipc_perm not msg_queue into the msg_queue security hooks
  shm/security: Pass kern_ipc_perm not shmid_kernel into the shm security hooks
  sem/security: Pass kern_ipc_perm not sem_array into the sem security hooks
  pidns: simpler allocation of pid_* caches
2018-04-03 19:15:32 -07:00
Dominik Brodowski
31c213f210 ipc: add msgsnd syscall/compat_syscall wrappers
Provide ksys_msgsnd() and compat_ksys_msgsnd() wrappers to avoid in-kernel
calls to these syscalls. The ksys_ prefix denotes that these functions are
meant as a drop-in replacement for the syscalls. In particular, they use
the same calling convention as sys_msgsnd() and compat_sys_msgsnd().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:28 +02:00
Dominik Brodowski
078faac9e8 ipc: add msgrcv syscall/compat_syscall wrappers
Provide ksys_msgrcv() and compat_ksys_msgrcv() wrappers to avoid in-kernel
calls to these syscalls. The ksys_ prefix denotes that these functions are
meant as a drop-in replacement for the syscalls. In particular, they use
the same calling convention as sys_msgrcv() and compat_sys_msgrcv().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:27 +02:00
Dominik Brodowski
e340db5648 ipc: add msgctl syscall/compat_syscall wrappers
Provide ksys_msgctl() and compat_ksys_msgctl() wrappers to avoid in-kernel
calls to these syscalls. The ksys_ prefix denotes that these functions are
meant as a drop-in replacement for the syscalls. In particular, they use
the same calling convention as sys_msgctl() and compat_sys_msgctl().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:26 +02:00
Dominik Brodowski
c84d0791df ipc: add shmctl syscall/compat_syscall wrappers
Provide ksys_shmctl() and compat_ksys_shmctl() wrappers to avoid in-kernel
calls to these syscalls. The ksys_ prefix denotes that these functions are
meant as a drop-in replacement for the syscalls. In particular, they use
the same calling convention as sys_shmctl() and compat_sys_shmctl().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:25 +02:00
Dominik Brodowski
da1e274434 ipc: add shmdt syscall wrapper
Provide ksys_shmdt() wrapper to avoid in-kernel calls to this syscall.
The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as sys_shmdt().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:25 +02:00
Dominik Brodowski
65749e0bb5 ipc: add shmget syscall wrapper
Provide ksys_shmget() wrapper to avoid in-kernel calls to this syscall.
The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as sys_shmget().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:24 +02:00
Dominik Brodowski
3d65661a49 ipc: add msgget syscall wrapper
Provide ksys_msgget() wrapper to avoid in-kernel calls to this syscall.
The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as sys_msgget().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:23 +02:00
Dominik Brodowski
d969c6fa72 ipc: add semctl syscall/compat_syscall wrappers
Provide ksys_semctl() and compat_ksys_semctl() wrappers to avoid in-kernel
calls to these syscalls. The ksys_ prefix denotes that these functions are
meant as a drop-in replacement for the syscalls. In particular, they use
the same calling convention as sys_semctl() and compat_sys_semctl().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:22 +02:00
Dominik Brodowski
69894718a5 ipc: add semget syscall wrapper
Provide ksys_semget() wrapper to avoid in-kernel calls to this syscall.
The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as sys_semget().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:22 +02:00
Dominik Brodowski
41f4f0e2f5 ipc: add semtimedop syscall/compat_syscall wrappers
Provide ksys_semtimedop() and compat_ksys_semtimedop() wrappers to avoid
in-kernel calls to these syscalls. The ksys_ prefix denotes that these
functions are meant as a drop-in replacement for the syscalls. In
particular, they use the same calling convention as sys_semtimedop() and
compat_sys_semtimedop().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:21 +02:00
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
Eric W. Biederman
f83a396d06 ipc: Move IPCMNI from include/ipc.h into ipc/util.h
The definition IPCMNI is only used in ipc/util.h and ipc/util.c.  So
there is no reason to keep it in a header file that the whole kernel
can see.  Move it into util.h to simplify future maintenance.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-24 11:25:36 -05:00
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
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
Linus Torvalds
cc73fee0ba Merge branch 'work.ipc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull ipc compat cleanup and 64-bit time_t from Al Viro:
 "IPC copyin/copyout sanitizing, including 64bit time_t work from Deepa
  Dinamani"

* 'work.ipc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  utimes: Make utimes y2038 safe
  ipc: shm: Make shmid_kernel timestamps y2038 safe
  ipc: sem: Make sem_array timestamps y2038 safe
  ipc: msg: Make msg_queue timestamps y2038 safe
  ipc: mqueue: Replace timespec with timespec64
  ipc: Make sys_semtimedop() y2038 safe
  get rid of SYSVIPC_COMPAT on ia64
  semtimedop(): move compat to native
  shmat(2): move compat to native
  msgrcv(2), msgsnd(2): move compat to native
  ipc(2): move compat to native
  ipc: make use of compat ipc_perm helpers
  semctl(): move compat to native
  semctl(): separate all layout-dependent copyin/copyout
  msgctl(): move compat to native
  msgctl(): split the actual work from copyin/copyout
  ipc: move compat shmctl to native
  shmctl: split the work from copyin/copyout
2017-09-14 17:37:26 -07:00
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
Al Viro
c0ebccb6fa semctl(): move compat to native
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-07-15 20:46:44 -04:00
Al Viro
553f770ef7 ipc: move compat shmctl to native
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-07-15 20:46:42 -04:00
Manfred Spraul
62b49c9908 ipc/util.h: update documentation for ipc_getref() and ipc_putref()
Now that ipc_rcu_alloc() and ipc_rcu_free() are removed, document when
it is valid to use ipc_getref() and ipc_putref().

Link: http://lkml.kernel.org/r/20170525185107.12869-21-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 16:26:02 -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
Eric W. Biederman
2bcb988366 ipc: Remove unused declaration of recompute_msgmni
The function recompute_msgmni was removed a while ago
but it is still declared in a header file remove it.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-04-17 21:53:07 -05:00
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
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
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
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
Manfred Spraul
239521f31d ipc: whitespace cleanup
The ipc code does not adhere the typical linux coding style.
This patch fixes lots of simple whitespace errors.

- mostly autogenerated by
  scripts/checkpatch.pl -f --fix \
	--types=pointer_location,spacing,space_before_tab
- one manual fixup (keep structure members tab-aligned)
- removal of additional space_before_tab that were not found by --fix

Tested with some of my msg and sem test apps.

Andrew: Could you include it in -mm and move it towards Linus' tree?

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Suggested-by: Li Bin <huawei.libin@huawei.com>
Cc: Joe Perches <joe@perches.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-27 21:02:39 -08:00
Rafael Aquini
72a8ff2f92 ipc: change kern_ipc_perm.deleted type to bool
struct kern_ipc_perm.deleted is meant to be used as a boolean toggle, and
the changes introduced by this patch are just to make the case explicit.

Signed-off-by: Rafael Aquini <aquini@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Acked-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>
2014-01-27 21:02:39 -08:00
Rafael Aquini
0f3d2b0135 ipc: introduce ipc_valid_object() helper to sort out IPC_RMID races
After the locking semantics for the SysV IPC API got improved, a couple
of IPC_RMID race windows were opened because we ended up dropping the
'kern_ipc_perm.deleted' check performed way down in ipc_lock().  The
spotted races got sorted out by re-introducing the old test within the
racy critical sections.

This patch introduces ipc_valid_object() to consolidate the way we cope
with IPC_RMID races by using the same abstraction across the API
implementation.

Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Greg Thelen <gthelen@google.com>
Reviewed-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>
2014-01-27 21:02:39 -08:00
Mathias Krause
4e9b45a192 ipc, msg: fix message length check for negative values
On 64 bit systems the test for negative message sizes is bogus as the
size, which may be positive when evaluated as a long, will get truncated
to an int when passed to load_msg().  So a long might very well contain a
positive value but when truncated to an int it would become negative.

That in combination with a small negative value of msg_ctlmax (which will
be promoted to an unsigned type for the comparison against msgsz, making
it a big positive value and therefore make it pass the check) will lead to
two problems: 1/ The kmalloc() call in alloc_msg() will allocate a too
small buffer as the addition of alen is effectively a subtraction.  2/ The
copy_from_user() call in load_msg() will first overflow the buffer with
userland data and then, when the userland access generates an access
violation, the fixup handler copy_user_handle_tail() will try to fill the
remainder with zeros -- roughly 4GB.  That almost instantly results in a
system crash or reset.

  ,-[ Reproducer (needs to be run as root) ]--
  | #include <sys/stat.h>
  | #include <sys/msg.h>
  | #include <unistd.h>
  | #include <fcntl.h>
  |
  | int main(void) {
  |     long msg = 1;
  |     int fd;
  |
  |     fd = open("/proc/sys/kernel/msgmax", O_WRONLY);
  |     write(fd, "-1", 2);
  |     close(fd);
  |
  |     msgsnd(0, &msg, 0xfffffff0, IPC_NOWAIT);
  |
  |     return 0;
  | }
  '---

Fix the issue by preventing msgsz from getting truncated by consistently
using size_t for the message length.  This way the size checks in
do_msgsnd() could still be passed with a negative value for msg_ctlmax but
we would fail on the buffer allocation in that case and error out.

Also change the type of m_ts from int to size_t to avoid similar nastiness
in other code paths -- it is used in similar constructs, i.e.  signed vs.
unsigned checks.  It should never become negative under normal
circumstances, though.

Setting msg_ctlmax to a negative value is an odd configuration and should
be prevented.  As that might break existing userland, it will be handled
in a separate commit so it could easily be reverted and reworked without
reintroducing the above described bug.

Hardening mechanisms for user copy operations would have catched that bug
early -- e.g.  checking slab object sizes on user copy operations as the
usercopy feature of the PaX patch does.  Or, for that matter, detect the
long vs.  int sign change due to truncation, as the size overflow plugin
of the very same patch does.

[akpm@linux-foundation.org: fix i386 min() warnings]
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Pax Team <pageexec@freemail.hu>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: <stable@vger.kernel.org>	[ v2.3.27+ -- yes, that old ;) ]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-13 12:09:36 +09:00
Davidlohr Bueso
53dad6d3a8 ipc: fix race with LSMs
Currently, IPC mechanisms do security and auditing related checks under
RCU.  However, since security modules can free the security structure,
for example, through selinux_[sem,msg_queue,shm]_free_security(), we can
race if the structure is freed before other tasks are done with it,
creating a use-after-free condition.  Manfred illustrates this nicely,
for instance with shared mem and selinux:

 -> do_shmat calls rcu_read_lock()
 -> do_shmat calls shm_object_check().
     Checks that the object is still valid - but doesn't acquire any locks.
     Then it returns.
 -> do_shmat calls security_shm_shmat (e.g. selinux_shm_shmat)
 -> selinux_shm_shmat calls ipc_has_perm()
 -> ipc_has_perm accesses ipc_perms->security

shm_close()
 -> shm_close acquires rw_mutex & shm_lock
 -> shm_close calls shm_destroy
 -> shm_destroy calls security_shm_free (e.g. selinux_shm_free_security)
 -> selinux_shm_free_security calls ipc_free_security(&shp->shm_perm)
 -> ipc_free_security calls kfree(ipc_perms->security)

This patch delays the freeing of the security structures after all RCU
readers are done.  Furthermore it aligns the security life cycle with
that of the rest of IPC - freeing them based on the reference counter.
For situations where we need not free security, the current behavior is
kept.  Linus states:

 "... the old behavior was suspect for another reason too: having the
  security blob go away from under a user sounds like it could cause
  various other problems anyway, so I think the old code was at least
  _prone_ to bugs even if it didn't have catastrophic behavior."

I have tested this patch with IPC testcases from LTP on both my
quad-core laptop and on a 64 core NUMA server.  In both cases selinux is
enabled, and tests pass for both voluntary and forced preemption models.
While the mentioned races are theoretical (at least no one as reported
them), I wanted to make sure that this new logic doesn't break anything
we weren't aware of.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-24 09:36:53 -07:00
Davidlohr Bueso
20b8875abc ipc: drop ipc_lock_check
No remaining users, we now use ipc_obtain_object_check().

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.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>
2013-09-11 15:59:45 -07:00
Davidlohr Bueso
32a2750010 ipc: drop ipc_lock_by_ptr
After previous cleanups and optimizations, this function is no longer
heavily used and we don't have a good reason to keep it.  Update the few
remaining callers and get rid of it.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.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>
2013-09-11 15:59:44 -07:00
Davidlohr Bueso
d9a605e40b ipc: rename ids->rw_mutex
Since in some situations the lock can be shared for readers, we shouldn't
be calling it a mutex, rename it to rwsem.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.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>
2013-09-11 15:59:42 -07:00
Davidlohr Bueso
3b1c4ad377 ipc: drop ipcctl_pre_down
Now that sem, msgque and shm, through *_down(), all use the lockless
variant of ipcctl_pre_down(), go ahead and delete it.

[akpm@linux-foundation.org: fix function name in kerneldoc, cleanups]
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.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>
2013-09-11 15:59:39 -07:00
Davidlohr Bueso
cf9d5d78d0 ipc: close open coded spin lock calls
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09 10:33:27 -07:00
Davidlohr Bueso
1ca7003ab4 ipc: introduce ipc object locking helpers
Simple helpers around the (kern_ipc_perm *)->lock spinlock.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09 10:33:27 -07:00
Rik van Riel
6062a8dc05 ipc,sem: fine grained locking for semtimedop
Introduce finer grained locking for semtimedop, to handle the common case
of a program wanting to manipulate one semaphore from an array with
multiple semaphores.

If the call is a semop manipulating just one semaphore in an array with
multiple semaphores, only take the lock for that semaphore itself.

If the call needs to manipulate multiple semaphores, or another caller is
in a transaction that manipulates multiple semaphores, the sem_array lock
is taken, as well as all the locks for the individual semaphores.

On a 24 CPU system, performance numbers with the semop-multi
test with N threads and N semaphores, look like this:

	vanilla		Davidlohr's	Davidlohr's +	Davidlohr's +
threads			patches		rwlock patches	v3 patches
10	610652		726325		1783589		2142206
20	341570		365699		1520453		1977878
30	288102		307037		1498167		2037995
40	290714		305955		1612665		2256484
50	288620		312890		1733453		2650292
60	289987		306043		1649360		2388008
70	291298		306347		1723167		2717486
80	290948		305662		1729545		2763582
90	290996		306680		1736021		2757524
100	292243		306700		1773700		3059159

[davidlohr.bueso@hp.com: do not call sem_lock when bogus sma]
[davidlohr.bueso@hp.com: make refcounter atomic]
Signed-off-by: Rik van Riel <riel@redhat.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Cc: Jason Low <jason.low2@hp.com>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: Emmanuel Benisty <benisty.e@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 08:12:58 -07:00
Davidlohr Bueso
16df3674ef ipc,sem: do not hold ipc lock more than necessary
Instead of holding the ipc lock for permissions and security checks, among
others, only acquire it when necessary.

Some numbers....

1) With Rik's semop-multi.c microbenchmark we can see the following
   results:

Baseline (3.9-rc1):
cpus 4, threads: 256, semaphores: 128, test duration: 30 secs
total operations: 151452270, ops/sec 5048409

+  59.40%            a.out  [kernel.kallsyms]  [k] _raw_spin_lock
+   6.14%            a.out  [kernel.kallsyms]  [k] sys_semtimedop
+   3.84%            a.out  [kernel.kallsyms]  [k] avc_has_perm_flags
+   3.64%            a.out  [kernel.kallsyms]  [k] __audit_syscall_exit
+   2.06%            a.out  [kernel.kallsyms]  [k] copy_user_enhanced_fast_string
+   1.86%            a.out  [kernel.kallsyms]  [k] ipc_lock

With this patchset:
cpus 4, threads: 256, semaphores: 128, test duration: 30 secs
total operations: 273156400, ops/sec 9105213

+  18.54%            a.out  [kernel.kallsyms]  [k] _raw_spin_lock
+  11.72%            a.out  [kernel.kallsyms]  [k] sys_semtimedop
+   7.70%            a.out  [kernel.kallsyms]  [k] ipc_has_perm.isra.21
+   6.58%            a.out  [kernel.kallsyms]  [k] avc_has_perm_flags
+   6.54%            a.out  [kernel.kallsyms]  [k] __audit_syscall_exit
+   4.71%            a.out  [kernel.kallsyms]  [k] ipc_obtain_object_check

2) While on an Oracle swingbench DSS (data mining) workload the
   improvements are not as exciting as with Rik's benchmark, we can see
   some positive numbers.  For an 8 socket machine the following are the
   percentages of %sys time incurred in the ipc lock:

Baseline (3.9-rc1):
100 swingbench users: 8,74%
400 swingbench users: 21,86%
800 swingbench users: 84,35%

With this patchset:
100 swingbench users: 8,11%
400 swingbench users: 19,93%
800 swingbench users: 77,69%

[riel@redhat.com: fix two locking bugs]
[sasha.levin@oracle.com: prevent releasing RCU read lock twice in semctl_main]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Chegu Vinod <chegu_vinod@hp.com>
Acked-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Emmanuel Benisty <benisty.e@gmail.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 08:12:58 -07:00
Davidlohr Bueso
444d0f621b ipc: introduce lockless pre_down ipcctl
Various forms of ipc use ipcctl_pre_down() to retrieve an ipc object and
check permissions, mostly for IPC_RMID and IPC_SET commands.

Introduce ipcctl_pre_down_nolock(), a lockless version of this function.
The locking version is retained, yet modified to call the nolock version
without affecting its semantics, thus transparent to all ipc callers.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Cc: Emmanuel Benisty <benisty.e@gmail.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 08:12:58 -07:00
Davidlohr Bueso
4d2bff5eb8 ipc: introduce obtaining a lockless ipc object
Through ipc_lock() and therefore ipc_lock_check() we currently return the
locked ipc object.  This is not necessary for all situations and can,
therefore, cause unnecessary ipc lock contention.

Introduce analogous ipc_obtain_object() and ipc_obtain_object_check()
functions that only lookup and return the ipc object.

Both these functions must be called within the RCU read critical section.

[akpm@linux-foundation.org: propagate the ipc_obtain_object() errno from ipc_lock()]
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Chegu Vinod <chegu_vinod@hp.com>
Acked-by: Michel Lespinasse <walken@google.com>
Cc: Emmanuel Benisty <benisty.e@gmail.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 08:12:57 -07:00
Davidlohr Bueso
7bb4deff61 ipc: remove bogus lock comment for ipc_checkid
This series makes the sysv semaphore code more scalable, by reducing the
time the semaphore lock is held, and making the locking more scalable for
semaphore arrays with multiple semaphores.

The first four patches were written by Davidlohr Buesso, and reduce the
hold time of the semaphore lock.

The last three patches change the sysv semaphore code locking to be more
fine grained, providing a performance boost when multiple semaphores in a
semaphore array are being manipulated simultaneously.

On a 24 CPU system, performance numbers with the semop-multi
test with N threads and N semaphores, look like this:

	vanilla		Davidlohr's	Davidlohr's +	Davidlohr's +
	threads			patches		rwlock patches	v3 patches
	10	610652		726325		1783589		2142206
	20	341570		365699		1520453		1977878
	30	288102		307037		1498167		2037995
	40	290714		305955		1612665		2256484
	50	288620		312890		1733453		2650292
	60	289987		306043		1649360		2388008
	70	291298		306347		1723167		2717486
	80	290948		305662		1729545		2763582
	90	290996		306680		1736021		2757524
	100	292243		306700		1773700		3059159

This patch:

There is no reason to be holding the ipc lock while reading ipcp->seq,
hence remove misleading comment.

Also simplify the return value for the function.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Cc: Emmanuel Benisty <benisty.e@gmail.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 08:12:57 -07:00
Stanislav Kinsbursky
4a674f34ba ipc: introduce message queue copy feature
This patch is required for checkpoint/restore in userspace.

c/r requires some way to get all pending IPC messages without deleting
them from the queue (checkpoint can fail and in this case tasks will be
resumed, so queue have to be valid).

To achive this, new operation flag MSG_COPY for sys_msgrcv() system call
was introduced.  If this flag was specified, then mtype is interpreted as
number of the message to copy.

If MSG_COPY is set, then kernel will allocate dummy message with passed
size, and then use new copy_msg() helper function to copy desired message
(instead of unlinking it from the queue).

Notes:

1) Return -ENOSYS if MSG_COPY is specified, but
   CONFIG_CHECKPOINT_RESTORE is not set.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-01-04 16:11:45 -08:00