Commit 6f568ebe authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Thomas Gleixner

futex: Fix barrier comment

The current comment for the barrier that guarantees that waiter increment
is always before taking the hb spinlock (barrier (A)) needs to be fixed as
it is misplaced.

This is obviously referring to hb_waiters_inc, which is a full barrier.
Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190206185602.949-1-dave@stgolabs.net
parent 74e96711
...@@ -2221,11 +2221,11 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) ...@@ -2221,11 +2221,11 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q)
* decrement the counter at queue_unlock() when some error has * decrement the counter at queue_unlock() when some error has
* occurred and we don't end up adding the task to the list. * occurred and we don't end up adding the task to the list.
*/ */
hb_waiters_inc(hb); hb_waiters_inc(hb); /* implies smp_mb(); (A) */
q->lock_ptr = &hb->lock; q->lock_ptr = &hb->lock;
spin_lock(&hb->lock); /* implies smp_mb(); (A) */ spin_lock(&hb->lock);
return hb; return hb;
} }
......
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