From 0b0577f6080c0645b079dcc03fdbaf40d928beb8 Mon Sep 17 00:00:00 2001 From: Manfred Spraul <manfred@colorfullife.com> Date: Wed, 2 Nov 2011 13:38:52 -0700 Subject: [PATCH] ipc/sem.c: handle spurious wakeups semtimedop() does not handle spurious wakeups, it returns -EINTR to user space. Most other schedule() users would just loop and not return to user space. The patch adds such a loop to semtimedop() Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- ipc/sem.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/ipc/sem.c b/ipc/sem.c index fb13be17945b2..227948f28ce63 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -1426,6 +1426,8 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, queue.status = -EINTR; queue.sleeper = current; + +sleep_again: current->state = TASK_INTERRUPTIBLE; sem_unlock(sma); @@ -1478,6 +1480,13 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, */ if (timeout && jiffies_left == 0) error = -EAGAIN; + + /* + * If the wakeup was spurious, just retry + */ + if (error == -EINTR && !signal_pending(current)) + goto sleep_again; + unlink_queue(sma, &queue); out_unlock_free: -- GitLab