Messages in this thread Patch in this message | | | From | Omar Sandoval <> | Subject | [PATCH] sched/wait: fix add_wait_queue() behavior change | Date | Tue, 5 Dec 2017 23:15:31 -0800 |
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From: Omar Sandoval <osandov@fb.com>
Commit 50816c48997a ("sched/wait: Standardize internal naming of wait-queue entries") changed the behavior of add_wait_queue() from inserting the wait entry at the head of the wait queue to the tail of the wait queue. That commit was a cleanup and didn't mention any functional changes so it was likely unintentional. This change in behavior theoretically breaks wait queues which mix exclusive and non-exclusive waiters, as non-exclusive waiters will not be woken up if they are queued behind enough exclusive waiters.
Signed-off-by: Omar Sandoval <osandov@fb.com> --- Since Ingo hasn't replied, here's a proper patch.
kernel/sched/wait.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c index 98feab7933c7..929ecb7d6b78 100644 --- a/kernel/sched/wait.c +++ b/kernel/sched/wait.c @@ -27,7 +27,7 @@ void add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE; spin_lock_irqsave(&wq_head->lock, flags); - __add_wait_queue_entry_tail(wq_head, wq_entry); + __add_wait_queue(wq_head, wq_entry); spin_unlock_irqrestore(&wq_head->lock, flags); } EXPORT_SYMBOL(add_wait_queue); -- 2.15.1
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