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 <[email protected]> Reported-by: Peter Zijlstra <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Mike Galbraith <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
niw · Nov 2, 2011 · 0b0577f · 0b0577f
1 parent 3c24783
commit 0b0577f
Showing 1 changed file with 9 additions and 0 deletions.
diff --git 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: