23 Mar, 2018
1 commit
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All of the users are now in ipc/sem.c so make the definitions
local to that file to make code maintenance easier. AKA
to prevent rebuilding the entire kernel when one of these
files is changed.Signed-off-by: "Eric W. Biederman"
02 Nov, 2017
1 commit
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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
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
15 Sep, 2017
1 commit
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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
04 Sep, 2017
1 commit
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time_t is not y2038 safe. Replace all uses of
time_t by y2038 safe time64_t.Similarly, replace the calls to get_seconds() with
y2038 safe ktime_get_real_seconds().
Note that this preserves fast access on 64 bit systems,
but 32 bit systems need sequence counters.The syscall interface themselves are not changed as part of
the patch. They will be part of a different series.Signed-off-by: Deepa Dinamani
Reviewed-by: Arnd Bergmann
Signed-off-by: Al Viro
19 Jul, 2017
1 commit
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Pull structure randomization updates from Kees Cook:
"Now that IPC and other changes have landed, enable manual markings for
randstruct plugin, including the task_struct.This is the rest of what was staged in -next for the gcc-plugins, and
comes in three patches, largest first:- mark "easy" structs with __randomize_layout
- mark task_struct with an optional anonymous struct to isolate the
__randomize_layout section- mark structs to opt _out_ of automated marking (which will come
later)And, FWIW, this continues to pass allmodconfig (normal and patched to
enable gcc-plugins) builds of x86_64, i386, arm64, arm, powerpc, and
s390 for me"* tag 'gcc-plugins-v4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
randstruct: opt-out externally exposed function pointer structs
task_struct: Allow randomized layout
randstruct: Mark various structs for randomization
13 Jul, 2017
2 commits
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sem_ctime is initialized to the semget() time and then updated at every
semctl() that changes the array.Thus it does not represent the time of the last change.
Especially, semop() calls are only stored in sem_otime, not in
sem_ctime.This is already described in ipc/sem.c, I just overlooked that there is
a comment in include/linux/sem.h and man semctl(2) as well.So: Correct wrong comments.
Link: http://lkml.kernel.org/r/20170515171912.6298-4-manfred@colorfullife.com
Signed-off-by: Manfred Spraul
Cc: Kees Cook
Cc:
Cc: Davidlohr Bueso
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Fabian Frederick
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
sma->sem_base is initialized with
sma->sem_base = (struct sem *) &sma[1];
The current code has four problems:
- There is an unnecessary pointer dereference - sem_base is not needed.
- Alignment for struct sem only works by chance.
- The current code causes false positive for static code analysis.
- This is a cast between different non-void types, which the future
randstruct GCC plugin warns on.And, as bonus, the code size gets smaller:
Before:
0 .text 00003770
After:
0 .text 0000374e[manfred@colorfullife.com: s/[0]/[]/, per hch]
Link: http://lkml.kernel.org/r/20170525185107.12869-2-manfred@colorfullife.com
Link: http://lkml.kernel.org/r/20170515171912.6298-2-manfred@colorfullife.com
Signed-off-by: Manfred Spraul
Acked-by: Kees Cook
Cc: Kees Cook
Cc:
Cc: Davidlohr Bueso
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Fabian Frederick
Cc: Christoph Hellwig
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Jul, 2017
1 commit
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This marks many critical kernel structures for randomization. These are
structures that have been targeted in the past in security exploits, or
contain functions pointers, pointers to function pointer tables, lists,
workqueues, ref-counters, credentials, permissions, or are otherwise
sensitive. This initial list was extracted from Brad Spengler/PaX Team's
code in the last public patch of grsecurity/PaX based on my understanding
of the code. Changes or omissions from the original code are mine and
don't reflect the original grsecurity/PaX code.Left out of this list is task_struct, which requires special handling
and will be covered in a subsequent patch.Signed-off-by: Kees Cook
09 May, 2017
1 commit
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Assign 'struct kern_ipc_perm' its own cacheline to avoid false sharing
with sysv ipc calls.While the structure itself is rather read-mostly throughout the lifespan
of ipc, the spinlock causes most of the invalidations. One example is
commit 31a7c4746e9 ("ipc/sem.c: cacheline align the ipc spinlock for
semaphores"). Therefore, extend this to all ipc.The effect of cacheline alignment on sems can be seen in sembench, which
deals mostly with semtimedop wait/wakes is seen to improve raw
throughput (worker loops) between 8 to 12% on a 24-core x86 with over 4
threads.Link: http://lkml.kernel.org/r/1486673582-6979-4-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso
Cc: Manfred Spraul
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
28 Feb, 2017
1 commit
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sysv sem has two lock modes: One with per-semaphore locks, one lock mode
with a single global lock for the whole array. When switching from the
per-semaphore locks to the global lock, all per-semaphore locks must be
scanned for ongoing operations.The patch adds a hysteresis for switching from the global lock to the
per semaphore locks. This reduces how often the per-semaphore locks
must be scanned.Compared to the initial patch, this is a simplified solution: Setting
USE_GLOBAL_LOCK_HYSTERESIS to 1 restores the current behavior.In theory, a workload with exactly 10 simple sops and then one complex
op now scales a bit worse, but this is pure theory: If there is
concurrency, the it won't be exactly 10:1:10:1:10:1:... If there is no
concurrency, then there is no need for scalability.Link: http://lkml.kernel.org/r/1476851896-3590-3-git-send-email-manfred@colorfullife.com
Signed-off-by: Manfred Spraul
Cc: Peter Zijlstra
Cc: Davidlohr Bueso
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: H. Peter Anvin
Cc:
Cc: kernel test robot
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Oct, 2016
1 commit
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Commit 6d07b68ce16a ("ipc/sem.c: optimize sem_lock()") introduced a
race:sem_lock has a fast path that allows parallel simple operations.
There are two reasons why a simple operation cannot run in parallel:
- a non-simple operations is ongoing (sma->sem_perm.lock held)
- a complex operation is sleeping (sma->complex_count != 0)As both facts are stored independently, a thread can bypass the current
checks by sleeping in the right positions. See below for more details
(or kernel bugzilla 105651).The patch fixes that by creating one variable (complex_mode)
that tracks both reasons why parallel operations are not possible.The patch also updates stale documentation regarding the locking.
With regards to stable kernels:
The patch is required for all kernels that include the
commit 6d07b68ce16a ("ipc/sem.c: optimize sem_lock()") (3.10?)The alternative is to revert the patch that introduced the race.
The patch is safe for backporting, i.e. it makes no assumptions
about memory barriers in spin_unlock_wait().Background:
Here is the race of the current implementation:Thread A: (simple op)
- does the first "sma->complex_count == 0" testThread B: (complex op)
- does sem_lock(): This includes an array scan. But the scan can't
find Thread A, because Thread A does not own sem->lock yet.
- the thread does the operation, increases complex_count,
drops sem_lock, sleepsThread A:
- spin_lock(&sem->lock), spin_is_locked(sma->sem_perm.lock)
- sleeps before the complex_count testThread C: (complex op)
- does sem_lock (no array scan, complex_count==1)
- wakes up Thread B.
- decrements complex_countThread A:
- does the complex_count testBug:
Now both thread A and thread C operate on the same array, without
any synchronization.Fixes: 6d07b68ce16a ("ipc/sem.c: optimize sem_lock()")
Link: http://lkml.kernel.org/r/1469123695-5661-1-git-send-email-manfred@colorfullife.com
Reported-by:
Cc: "H. Peter Anvin"
Cc: Peter Zijlstra
Cc: Davidlohr Bueso
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc:
Cc: [3.10+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
10 Jul, 2013
2 commits
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sem_otime contains the time of the last semaphore operation that
completed successfully. Every operation updates this value, thus access
from multiple cpus can cause thrashing.Therefore the patch replaces the variable with a per-semaphore variable.
The per-array sem_otime is only calculated when required.No performance improvement on a single-socket i3 - only important for
larger systems.Signed-off-by: Manfred Spraul
Cc: Rik van Riel
Cc: Davidlohr Bueso
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Introduce separate queues for operations that do not modify the
semaphore values. Advantages:- Simpler logic in check_restart().
- Faster update_queue(): Right now, all wait-for-zero operations are
always tested, even if the semaphore value is not 0.
- wait-for-zero gets again priority, as in linux
Cc: Rik van Riel
Cc: Davidlohr Bueso
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Oct, 2012
1 commit
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Signed-off-by: David Howells
Acked-by: Arnd Bergmann
Acked-by: Thomas Gleixner
Acked-by: Michael Kerrisk
Acked-by: Paul E. McKenney
Acked-by: Dave Jones
03 Nov, 2011
2 commits
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For the sysvsem undo, each task struct contains a sysv_sem structure with
a pointer to the undo information.This pointer is only necessary if sysvipc is enabled - thus the pointer
can be made conditional on CONFIG_SYSVIPC.Signed-off-by: Manfred Spraul
Acked-by: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Mike Galbraith
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
include/linux/sem.h contains several structures that are only used within
ipc/sem.c.The patch moves them into ipc/sem.c - there is no need to expose the
structures to the whole kernel.No functional changes, only whitespace cleanups and 80-char per line
fixes.Signed-off-by: Manfred Spraul
Acked-by: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Mike Galbraith
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Jul, 2011
1 commit
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This allows us to move duplicated code in
(atomic_inc_not_zero() for now) toSigned-off-by: Arun Sharma
Reviewed-by: Eric Dumazet
Cc: Ingo Molnar
Cc: David Miller
Cc: Eric Dumazet
Acked-by: Mike Frysinger
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
28 May, 2010
1 commit
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Cacheline align the spinlock for sysv semaphores. Without the patch, the
spinlock and sem_otime [written by every semop that modified the array]
and sem_base [read in the hot path of try_atomic_semop()] can be in the
same cacheline.Signed-off-by: Manfred Spraul
Cc: Chris Mason
Cc: Zach Brown
Cc: Jens Axboe
Cc: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Dec, 2009
1 commit
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Based on Nick's findings:
sysv sem has the concept of semaphore arrays that consist out of multiple
semaphores. Atomic operations that affect multiple semaphores are
supported.The patch is the first step for optimizing simple, single semaphore
operations: In addition to the global list of all pending operations, a
2nd, per-semaphore list with the simple operations is added.Note: this patch does not make sense by itself, the new list is used
nowhere.Signed-off-by: Manfred Spraul
Cc: Nick Piggin
Cc: Pierre Peiffer
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Jul, 2008
4 commits
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The attached patch:
- reverses the locking order of ulp->lock and sem_lock:
Previously, it was first ulp->lock, then inside sem_lock.
Now it's the other way around.
- converts the undo structure to rcu.Benefits:
- With the old locking order, IPC_RMID could not kfree the undo structures.
The stale entries remained in the linked lists and were released later.
- The patch fixes a a race in semtimedop(): if both IPC_RMID and a semget() that
recreates exactly the same id happen between find_alloc_undo() and sem_lock,
then semtimedop() would access already kfree'd memory.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul
Reviewed-by: Nadia Derbey
Cc: Pierre Peiffer
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
sem_array.sem_pending is a double linked list, the attached patch converts
it to struct list_head.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul
Reviewed-by: Nadia Derbey
Cc: Pierre Peiffer
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
sem_queue.sma and sem_queue.id were never used, the attached patch removes
them.Signed-off-by: Manfred Spraul
Reviewed-by: Nadia Derbey
Cc: Pierre Peiffer
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The undo structures contain two linked lists, the attached patch replaces
them with generic struct list_head lists.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul
Cc: Nadia Derbey
Cc: Pierre Peiffer
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 Oct, 2007
1 commit
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This patch introduces ipcs storage into IDRs. The main changes are:
. This ipc_ids structure is changed: the entries array is changed into a
root idr structure.
. The grow_ary() routine is removed: it is not needed anymore when adding
an ipc structure, since we are now using the IDR facility.
. The ipc_rmid() routine interface is changed:
. there is no need for this routine to return the pointer passed in as
argument: it is now declared as a void
. since the id is now part of the kern_ipc_perm structure, no need to
have it as an argument to the routineSigned-off-by: Nadia Derbey
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Apr, 2006
1 commit
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Signed-off-by: David Woodhouse
07 Nov, 2005
1 commit
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Fix more include file problems that surfaced since I submitted the previous
fix-missing-includes.patch. This should now allow not to include sched.h
from module.h, which is done by a followup patch.Signed-off-by: Tim Schmielau
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Sep, 2005
1 commit
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Change the /proc/sysvipc/shm|sem|msg files to use the generic seq_file
implementation for struct ipc_ids.Signed-off-by: Mike Waychison
Cc: Manfred Spraul
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Apr, 2005
1 commit
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.Let it rip!
