Commit-ID: 1b367ece0d7e696cab1c8501bab282cc6a538b3f Gitweb: http://git.kernel.org/tip/1b367ece0d7e696cab1c8501bab282cc6a538b3f Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Wed, 22 Mar 2017 11:35:49 +0100 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Thu, 23 Mar 2017 19:10:06 +0100
futex: Use smp_store_release() in mark_wake_futex() Since the futex_q can dissapear the instruction after assigning NULL, this really should be a RELEASE barrier. That stops loads from hitting dead memory too. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: juri.le...@arm.com Cc: bige...@linutronix.de Cc: xlp...@redhat.com Cc: rost...@goodmis.org Cc: mathieu.desnoy...@efficios.com Cc: jdesfos...@efficios.com Cc: dvh...@infradead.org Cc: bris...@redhat.com Link: http://lkml.kernel.org/r/20170322104151.604296...@infradead.org Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- kernel/futex.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 1531cc4..cc10340 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1290,8 +1290,7 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q) * memory barrier is required here to prevent the following * store to lock_ptr from getting ahead of the plist_del. */ - smp_wmb(); - q->lock_ptr = NULL; + smp_store_release(&q->lock_ptr, NULL); } static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *top_waiter,
