Commit fe1bce9e authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Thomas Gleixner

futex: Acknowledge a new waiter in counter before plist

Otherwise an incoming waker on the dest hash bucket can miss
the waiter adding itself to the plist during the lockless
check optimization (small window but still the correct way
of doing this); similarly to the decrement counterpart.
Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: bigeasy@linutronix.de
Cc: dvhart@infradead.org
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1461208164-29150-1-git-send-email-dave@stgolabs.netSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 89e9e66b
...@@ -1535,8 +1535,8 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1, ...@@ -1535,8 +1535,8 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
if (likely(&hb1->chain != &hb2->chain)) { if (likely(&hb1->chain != &hb2->chain)) {
plist_del(&q->list, &hb1->chain); plist_del(&q->list, &hb1->chain);
hb_waiters_dec(hb1); hb_waiters_dec(hb1);
plist_add(&q->list, &hb2->chain);
hb_waiters_inc(hb2); hb_waiters_inc(hb2);
plist_add(&q->list, &hb2->chain);
q->lock_ptr = &hb2->lock; q->lock_ptr = &hb2->lock;
} }
get_futex_key_refs(key2); get_futex_key_refs(key2);
......
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