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* ipc/msg: avoid waking sender upon full queueDavidlohr Bueso2016-10-111-10/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc/msg: make ss_wakeup() kill arg booleanDavidlohr Bueso2016-10-111-4/+4
| | | | | | | | | | | | ... 'tis annoying. Link: http://lkml.kernel.org/r/1469748819-19484-4-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc/msg: batch queue sender wakeupsDavidlohr Bueso2016-10-111-10/+20
| | | | | | | | | | | | | | | | | | | | | | | Currently the use of wake_qs in sysv msg queues are only for the receiver tasks that are blocked on the queue. But blocked sender tasks (due to queue size constraints) still are awoken with the ipc object lock held, which can be a problem particularly for small sized queues and far from gracious for -rt (just like it was for the receiver side). The paths that actually wakeup a sender are obviously related to when we are either getting rid of the queue or after (some) space is freed-up after a receiver takes the msg (msgrcv). Furthermore, with the exception of msgrcv, we can always piggy-back on expunge_all that has its own tasks lined-up for waking. Finally, upon unlinking the message, it should be no problem delaying the wakeups a bit until after we've released the lock. Link: http://lkml.kernel.org/r/1469748819-19484-3-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc/msg: implement lockless pipelined wakeupsSebastian Andrzej Siewior2016-10-111-93/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sysv, ipc: fix security-layer leakingFabian Frederick2016-08-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 53dad6d3a8e5 ("ipc: fix race with LSMs") updated ipc_rcu_putref() to receive rcu freeing function but used generic ipc_rcu_free() instead of msg_rcu_free() which does security cleaning. Running LTP msgsnd06 with kmemleak gives the following: cat /sys/kernel/debug/kmemleak unreferenced object 0xffff88003c0a11f8 (size 8): comm "msgsnd06", pid 1645, jiffies 4294672526 (age 6.549s) hex dump (first 8 bytes): 1b 00 00 00 01 00 00 00 ........ backtrace: kmemleak_alloc+0x23/0x40 kmem_cache_alloc_trace+0xe1/0x180 selinux_msg_queue_alloc_security+0x3f/0xd0 security_msg_queue_alloc+0x2e/0x40 newque+0x4e/0x150 ipcget+0x159/0x1b0 SyS_msgget+0x39/0x40 entry_SYSCALL_64_fastpath+0x13/0x8f Manfred Spraul suggested to fix sem.c as well and Davidlohr Bueso to only use ipc_rcu_free in case of security allocation failure in newary() Fixes: 53dad6d3a8e ("ipc: fix race with LSMs") Link: http://lkml.kernel.org/r/1470083552-22966-1-git-send-email-fabf@skynet.be Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Initialize msg/shm IPC objects before doing ipc_addid()Linus Torvalds2015-09-301-7/+7
| | | | | | | | | | | | | | | | | 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 e8577d1f0329: "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>
* ipc: rename ipc_obtain_objectDavidlohr Bueso2015-06-301-1/+1
| | | | | | | | | | ... 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>
* ipc,msg: provide barrier pairings for lockless receiveDavidlohr Bueso2015-06-301-10/+38
| | | | | | | | | | | | | | | | | | | We currently use a full barrier on the sender side to to avoid receiver tasks disappearing on us while still performing on the sender side wakeup. We lack however, the proper CPU-CPU interactions pairing on the receiver side which busy-waits for the message. Similarly, we do not need a full smp_mb, and can relax the semantics for the writer and reader sides of the message. This is safe as we are only ordering loads and stores to r_msg. And in both smp_wmb and smp_rmb, there are no stores after the calls _anyway_. This obviously applies for pipelined_send and expunge_all, for EIRDM when destroying a queue. 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>
* ipc: remove use of seq_printf return valueJoe Perches2015-04-151-16/+18
| | | | | | | | | | | | The seq_printf return value, because it's frequently misused, will eventually be converted to void. See: commit 1f33c41c03da ("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>
* ipc/msg: increase MSGMNI, remove scalingManfred Spraul2014-12-131-35/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* ipc,msg: document volatile r_msgDavidlohr Bueso2014-06-061-3/+7
| | | | | | | | | | The need for volatile is not obvious, document it. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc,msg: move some msgq ns code aroundDavidlohr Bueso2014-06-061-69/+63
| | | | | | | | | | | | Nothing big and no logical changes, just get rid of some redundant function declarations. Move msg_[init/exit]_ns down the end of the file. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc,msg: use current->state helpersDavidlohr Bueso2014-06-061-2/+2
| | | | | | | | | | Call __set_current_state() instead of assigning the new state directly. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Signed-off-by: Manfred Spraul <manfred@colorfullif.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc, kernel: clear whitespacePaul McQuade2014-06-061-16/+15
| | | | | | | | 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>
* ipc, kernel: use Linux headersPaul McQuade2014-06-061-1/+1
| | | | | | | | | Use #include <linux/uaccess.h> instead of <asm/uaccess.h> Use #include <linux/types.h> instead of <asm/types.h> 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>
* ipc: constify ipc_opsMathias Krause2014-06-061-5/+4
| | | | | | | | | | | | | | | | 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>
* ipc: Fix 2 bugs in msgrcv() MSG_COPY implementationMichael Kerrisk2014-03-161-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While testing and documenting the msgrcv() MSG_COPY flag that Stanislav Kinsbursky added in commit 4a674f34ba04 ("ipc: introduce message queue copy feature" => kernel 3.8), I discovered a couple of bugs in the implementation. The two bugs concern MSG_COPY interactions with other msgrcv() flags, namely: (A) MSG_COPY + MSG_EXCEPT (B) MSG_COPY + !IPC_NOWAIT The bugs are distinct (and the fix for the first one is obvious), however my fix for both is a single-line patch, which is why I'm combining them in a single mail, rather than writing two mails+patches. ===== (A) MSG_COPY + MSG_EXCEPT ===== With the addition of the MSG_COPY flag, there are now two msgrcv() flags--MSG_COPY and MSG_EXCEPT--that modify the meaning of the 'msgtyp' argument in unrelated ways. Specifying both in the same call is a logical error that is currently permitted, with the effect that MSG_COPY has priority and MSG_EXCEPT is ignored. The call should give an error if both flags are specified. The patch below implements that behavior. ===== (B) (B) MSG_COPY + !IPC_NOWAIT ===== The test code that was submitted in commit 3a665531a3b7 ("selftests: IPC message queue copy feature test") shows MSG_COPY being used in conjunction with IPC_NOWAIT. In other words, if there is no message at the position 'msgtyp'. return immediately with the error in ENOMSG. What was not (fully) tested is the behavior if MSG_COPY is specified *without* IPC_NOWAIT, and there is an odd behavior. If the queue contains less than 'msgtyp' messages, then the call blocks until the next message is written to the queue. At that point, the msgrcv() call returns a copy of the newly added message, regardless of whether that message is at the ordinal position 'msgtyp'. This is clearly bogus, and problematic for applications that might want to make use of the MSG_COPY flag. I considered the following possible solutions to this problem: (1) Force the call to block until a message *does* appear at the position 'msgtyp'. (2) If the MSG_COPY flag is specified, the kernel should implicitly add IPC_NOWAIT, so that the call fails with ENOMSG for this case. (3) If the MSG_COPY flag is specified, but IPC_NOWAIT is not, generate an error (probably, EINVAL is the right one). I do not know if any application would really want to have the functionality of solution (1), especially since an application can determine in advance the number of messages in the queue using msgctl() IPC_STAT. Obviously, this solution would be the most work to implement. Solution (2) would have the effect of silently fixing any applications that tried to employ broken behavior. However, it would mean that if we later decided to implement solution (1), then user-space could not easily detect what the kernel supports (but, since I'm somewhat doubtful that solution (1) is needed, I'm not sure that this is much of a problem). Solution (3) would have the effect of informing broken applications that they are doing something broken. The downside is that this would cause a ABI breakage for any applications that are currently employing the broken behavior. However: a) Those applications are almost certainly not getting the results they expect. b) Possibly, those applications don't even exist, because MSG_COPY is currently hidden behind CONFIG_CHECKPOINT_RESTORE. The upside of solution (3) is that if we later decided to implement solution (1), user-space could determine what the kernel supports, via the error return. In my view, solution (3) is mildly preferable to solution (2), and solution (1) could still be done later if anyone really cares. The patch below implements solution (3). PS. For anyone out there still listening, it's the usual story: documenting an API (and the thinking about, and the testing of the API, that documentation entails) is the one of the single best ways of finding bugs in the API, as I've learned from a lot of experience. Best to do that documentation before releasing the API. Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: stable@vger.kernel.org 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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc,msg: document barriersDavidlohr Bueso2014-01-271-2/+17
| | | | | | | | | | | | | | | | | | Both expunge_all() and pipeline_send() rely on both a nil msg value and a full barrier to guarantee the correct ordering when waking up a task. While its counterpart at the receiving end is well documented for the lockless recv algorithm, we still need to document these specific smp_mb() calls. [akpm@linux-foundation.org: fix typo, per Mike] [akpm@linux-foundation.org: mroe tpyos] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aswin Chandramouleeswaran <aswin@hp.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>
* ipc: whitespace cleanupManfred Spraul2014-01-271-9/+9
| | | | | | | | | | | | | | | | | | | | | | | 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>
* ipc: introduce ipc_valid_object() helper to sort out IPC_RMID racesRafael Aquini2014-01-271-3/+4
| | | | | | | | | | | | | | | | | | | | 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>
* ipc,msg: prevent race with rmid in msgsnd,msgrcvDavidlohr Bueso2013-09-301-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a race in both msgrcv() and msgsnd() between finding the msg and actually dealing with the queue, as another thread can delete shmid underneath us if we are preempted before acquiring the kern_ipc_perm.lock. Manfred illustrates this nicely: Assume a preemptible kernel that is preempted just after msq = msq_obtain_object_check(ns, msqid) in do_msgrcv(). The only lock that is held is rcu_read_lock(). Now the other thread processes IPC_RMID. When the first task is resumed, then it will happily wait for messages on a deleted queue. Fix this by checking for if the queue has been deleted after taking the lock. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Reported-by: Manfred Spraul <manfred@colorfullife.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: <stable@vger.kernel.org> [3.11] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: fix race with LSMsDavidlohr Bueso2013-09-241-6/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* ipc,msg: drop msg_unlockDavidlohr Bueso2013-09-111-3/+2
| | | | | | | | | | | | There is only one user left, drop this function and just call ipc_unlock_object() and rcu_read_unlock(). 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>
* ipc: rename ids->rw_mutexDavidlohr Bueso2013-09-111-10/+10
| | | | | | | | | | | | 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>
* ipc/msg.c: Fix lost wakeup in msgsnd().Manfred Spraul2013-09-031-7/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The check if the queue is full and adding current to the wait queue of pending msgsnd() operations (ss_add()) must be atomic. Otherwise: - the thread that performs msgsnd() finds a full queue and decides to sleep. - the thread that performs msgrcv() first reads all messages from the queue and then sleeps, because the queue is empty. - the msgrcv() calls do not perform any wakeups, because the msgsnd() task has not yet called ss_add(). - then the msgsnd()-thread first calls ss_add() and then sleeps. Net result: msgsnd() and msgrcv() both sleep forever. Observed with msgctl08 from ltp with a preemptible kernel. Fix: Call ipc_lock_object() before performing the check. The patch also moves security_msg_queue_msgsnd() under ipc_lock_object: - msgctl(IPC_SET) explicitely mentions that it tries to expunge any pending operations that are not allowed anymore with the new permissions. If security_msg_queue_msgsnd() is called without locks, then there might be races. - it makes the patch much simpler. Reported-and-tested-by: Vineet Gupta <Vineet.Gupta1@synopsys.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: stable@vger.kernel.org # for 3.11 Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* IPC: bugfix for msgrcv with msgtyp < 0Svenning Sørensen2013-08-281-2/+3
| | | | | | | | | | | | | | | | | | | | | According to 'man msgrcv': "If msgtyp is less than 0, the first message of the lowest type that is less than or equal to the absolute value of msgtyp shall be received." Bug: The kernel only returns a message if its type is 1; other messages with type < abs(msgtype) will never get returned. Fix: After having traversed the list to find the first message with the lowest type, we need to actually return that message. This regression was introduced by commit daaf74cf0867 ("ipc: refactor msg list search into separate function") Signed-off-by: Svenning Soerensen <sss@secomea.dk> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: remove unused functionsDavidlohr Bueso2013-07-091-25/+0
| | | | | | | | | | | We can now drop the msg_lock and msg_lock_check functions along with a bogus comment introduced previously in semctl_down. 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>
* ipc,msg: shorten critical region in msgrcvDavidlohr Bueso2013-07-091-26/+32
| | | | | | | | | | | | do_msgrcv() is the last msg queue function that abuses the ipc lock Take it only when needed when actually updating msq. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Rik van Riel <riel@redhat.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>
* ipc,msg: shorten critical region in msgsndDavidlohr Bueso2013-07-091-13/+24
| | | | | | | | | | | | do_msgsnd() is another function that does too many things with the ipc object lock acquired. Take it only when needed when actually updating msq. 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>
* ipc,msg: make msgctl_nolock locklessDavidlohr Bueso2013-07-091-10/+17
| | | | | | | | | | | | | | While the INFO cmd doesn't take the ipc lock, the STAT commands do acquire it unnecessarily. We can do the permissions and security checks only holding the rcu lock. This function now mimics semctl_nolock(). 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>
* ipc,msg: introduce lockless functions to obtain the ipc objectDavidlohr Bueso2013-07-091-0/+21
| | | | | | | | | | | | | Add msq_obtain_object() and msq_obtain_object_check(), which will allow us to get the ipc object without acquiring the lock. Just as with semaphores, these functions are basically wrappers around ipc_obtain_object*(). 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>
* ipc,msg: introduce msgctl_nolockDavidlohr Bueso2013-07-091-15/+34
| | | | | | | | | | | | | | | Similar to semctl, when calling msgctl, the *_INFO and *_STAT commands can be performed without acquiring the ipc object. Add a msgctl_nolock() function and move the logic of *_INFO and *_STAT out of msgctl(). This change still takes the lock and it will be properly lockless in the next patch 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>
* ipc,msg: shorten critical region in msgctl_downDavidlohr Bueso2013-07-091-5/+7
| | | | | | | | | | | | Instead of holding the ipc lock for the entire function, use the ipcctl_pre_down_nolock and only acquire the lock for specific commands: RMID and SET. 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>
* ipc: move locking out of ipcctl_pre_down_nolockDavidlohr Bueso2013-07-091-7/+17
| | | | | | | | | | | | | | | This function currently acquires both the rw_mutex and the rcu lock on successful lookups, leaving the callers to explicitly unlock them, creating another two level locking situation. Make the callers (including those that still use ipcctl_pre_down()) explicitly lock and unlock the rwsem and rcu lock. 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>
* ipc: close open coded spin lock callsDavidlohr Bueso2013-07-091-1/+1
| | | | | | | | 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>
* ipc: move rcu lock out of ipc_addidDavidlohr Bueso2013-07-091-4/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patchset continues the work that began in the sysv ipc semaphore scaling series, see https://lkml.org/lkml/2013/3/20/546 Just like semaphores used to be, sysv shared memory and msg queues also abuse the ipc lock, unnecessarily holding it for operations such as permission and security checks. This patchset mostly deals with mqueues, and while shared mem can be done in a very similar way, I want to get these patches out in the open first. It also does some pending cleanups, mostly focused on the two level locking we have in ipc code, taking care of ipc_addid() and ipcctl_pre_down_nolock() - yes there are still functions that need to be updated as well. This patch: Make all callers explicitly take and release the RCU read lock. This addresses the two level locking seen in newary(), newseg() and newqueue(). For the last two, explicitly unlock the ipc object and the rcu lock, instead of calling the custom shm_unlock and msg_unlock functions. The next patch will deal with the open coded locking for ->perm.lock 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>
* ipc/msg.c: use list_for_each_entry_[safe] for list traversingNikola Pajkovsky2013-05-011-27/+8
| | | | | | | | | | | | The ipc/msg.c code does its list operations by hand and it open-codes the accesses, instead of using for_each_entry_[safe]. Signed-off-by: Nikola Pajkovsky <npajkovs@redhat.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc,sem: fine grained locking for semtimedopRik van Riel2013-05-011-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* ipc: refactor msg list search into separate functionPeter Hurley2013-05-011-22/+26
| | | | | | | | [fengguang.wu@intel.com: find_msg can be static] Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: simplify msg list searchPeter Hurley2013-05-011-6/+2
| | | | | | | Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: implement MSG_COPY as a new receive modePeter Hurley2013-05-011-13/+9
| | | | | | | | | | | | | Teach the helper routines about MSG_COPY so that msgtyp is preserved as the message number to copy. The security functions affected by this change were audited and no additional changes are necessary. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: remove msg handling from queue scanPeter Hurley2013-05-011-10/+4
| | | | | | | | | | In preparation for refactoring the queue scan into a separate function, relocate msg copying. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: set msg back to -EAGAIN if copy wasn't performedStanislav Kinsbursky2013-04-021-0/+1
| | | | | | | | | | | | | Make sure that msg pointer is set back to error value in case of MSG_COPY flag is set and desired message to copy wasn't found. This garantees that msg is either a error pointer or a copy address. Otherwise the last message in queue will be freed without unlinking from the queue (which leads to memory corruption) and the dummy allocated copy won't be released. Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: don't allocate a copy larger than maxPeter Hurley2013-03-081-2/+4
| | | | | | | | | | | | When MSG_COPY is set, a duplicate message must be allocated for the copy before locking the queue. However, the copy could not be larger than was sent which is limited to msg_ctlmax. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: add more comments to message copying related codeStanislav Kinsbursky2013-01-041-0/+8
| | | | | | | | Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: simplify message copyingStanislav Kinsbursky2013-01-041-16/+9
| | | | | | | | | | | | | | | Remove the redundant and confusing fill_copy(). Also add copy_msg() check for error. In this case exit from the function have to be done instead of break, because further code interprets any error as EAGAIN. Also define copy_msg() for the case when CONFIG_CHECKPOINT_RESTORE is disabled. Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: convert prepare_copy() from macro to functionStanislav Kinsbursky2013-01-041-2/+9
| | | | | | | | | | | This code works if CONFIG_CHECKPOINT_RESTORE is disabled. [akpm@linux-foundation.org: remove __maybe_unused] Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: simplify free_copy() callStanislav Kinsbursky2013-01-041-6/+8
| | | | | | | | | | | | | | | Passing and checking of msgflg to free_copy() is redundant. This patch sets copy to NULL on declaration instead and checks for non-NULL in free_copy(). Note: in case of copy allocation failure, error is returned immediately. So no need to check for IS_ERR() in free_copy(). Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ipc: introduce message queue copy featureStanislav Kinsbursky2013-01-041-2/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* ipc: message queue receive cleanupStanislav Kinsbursky2013-01-041-21/+23
| | | | | | | | | | | | | | | | Move all message related manipulation into one function msg_fill(). Actually, two functions because of the compat one. [akpm@linux-foundation.org: checkpatch fixes] 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>
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