ptrace: task_clear_jobctl_trapping()->wake_up_bit() needs mb()
__wake_up_bit() checks waitqueue_active() and thus the caller needs mb()
as wake_up_bit() documents, fix task_clear_jobctl_trapping().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/signal.c b/kernel/signal.c
index 6e600aaa..9b5453e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -277,6 +277,7 @@
{
if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
task->jobctl &= ~JOBCTL_TRAPPING;
+ smp_mb(); /* advised by wake_up_bit() */
wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
}
}