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Manfred Spraul authored
sys_semtimedop() may return -EIDRM although the semaphore operation completed successfully: thread 1: thread 2: semtimedop(), sleeps semop(): * acquires sem_lock() semtimedop() woken up due to timeout sem_lock() loops * notices that thread 2 could be completed. * performs the operations that thread 2 is sleeping on. * marks the semaphore operation as IN_WAKEUP * drops sem_lock(), does wakeup, sets return code to 0 * thread delayed due to interrupt, whatever * returns to user space * thread still delayed semctl(IPC_RMID) * acquires sem_lock() * ipc_rmid(), ipcp->deleted=1 * drops sem_lock() * thread finally continues - but seem_lock() now fails due to ipcp->deleted == 1 * returns -EIDRM instead of 0 The fix is trivial: Always use the return code in queue.status. In real world, the race probably doesn't matter: If the semaphore array is destroyed, the app is probably not interested if the last operation succeeded or was already cancelled. Signed-off-by:
Manfred Spraul <manfred@colorfullife.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Mike Galbraith <efault@gmx.de> Acked-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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