Messages in this thread | | | Date | Fri, 2 Sep 2016 14:06:43 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() |
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On 09/02, Peter Zijlstra wrote: > > FWIW, the way the mutex code avoids this issue is by doing the > signal_pending test while holding the q->lock, that way its exclusive > with wakeup.
And __wait_event_interruptible_locked() too.
BTW it is buggy anyway, it needs the
- __add_wait_queue_tail(&(wq), &__wait); + if (exclusive) + __add_wait_queue_tail(&(wq), &__wait); + else + __add_wait_queue((&(wq), &__wait);
and in fact it should use __add_wait_queue_exclusive() so that we can remove another "if (exclusive)" but this is off-topic.
Yes, I considered this option, but to me the addtional finish_wait() looks simpler.
And, if you agree with this change I will try to change __wait_event() as well and kill abort_exclusive_wait().
And in this case we certainly do not want to check the "condition" with q->lock held, because this would mean that "condition" won't be able to take this lock.
Oleg.
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