diff options
| author | Davidlohr Bueso <dave@stgolabs.net> | 2016-04-20 20:09:24 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-05-04 14:48:43 -0700 |
| commit | ad4b209d192624e8587f4988171d624346913ddd (patch) | |
| tree | 26bdee892c3fb8af37bbe2ed70ff4ff09b139ed1 /kernel/futex.c | |
| parent | 61fc0ae42c498f8eb782733065d93da6817d28b4 (diff) | |
futex: Acknowledge a new waiter in counter before plist
commit fe1bce9e2107ba3a8faffe572483b6974201a0e6 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: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Davidlohr 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.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index eaa3a8dfd345..9d8163afd87c 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1484,8 +1484,8 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1, if (likely(&hb1->chain != &hb2->chain)) { plist_del(&q->list, &hb1->chain); hb_waiters_dec(hb1); - plist_add(&q->list, &hb2->chain); hb_waiters_inc(hb2); + plist_add(&q->list, &hb2->chain); q->lock_ptr = &hb2->lock; } get_futex_key_refs(key2); |