Commit b209872b authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Kamal Mostafa

futex: Acknowledge a new waiter in counter before plist

commit fe1bce9e upstream.

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
Link: http://lkml.kernel.org/r/1461208164-29150-1-git-send-email-dave@stgolabs.netSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
parent a9be4e96
...@@ -1395,8 +1395,8 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1, ...@@ -1395,8 +1395,8 @@ 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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