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Groups > linux.kernel > #1474604
| From | Oleg Nesterov <oleg@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 1/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() |
| Date | 2016-09-01 23:10 +0200 |
| Message-ID | <scHph-70l-87@gated-at.bofh.it> (permalink) |
| References | <saoK6-6YC-21@gated-at.bofh.it> <saoTM-7aM-39@gated-at.bofh.it> <scyvE-1dR-27@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 09/01, Peter Zijlstra wrote:
>
> So mixing INTERRUPTIBLE and UNINTERRUPTIBLE and then not using
> TASK_NORMAL for wakeups is a mis-feature/abuse of waitqueues IMO.
Heh, agreed. When I was doing this fix I suddenly realize that I do
not understand why do we have, say, wake_up_interruptible().
I mean, I can't imagine the "real" use-case when you actually want
to wake up only the INTERRUPTIBLE tasks and leave the UNINTERRUPTIBLE
sleeping. Exclusive or not.
It seems that wake_up_interruptible() is mostly used simply because
the caller knows that UNINTERRUPTIBLE waiters are not possible, this
is often the case.
> @@ -67,6 +70,16 @@ static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
> {
> wait_queue_t *curr, *next;
>
> +#ifdef CONFIG_DEBUG_WAITQUEUE
> + if (q->state != -1) {
> + /*
> + * WARN if we have INTERRUPTIBLE and UNINTERRUPTIBLE
> + * waiters and do not use TASK_NORMAL to wake.
> + */
> + WARN_ON_ONCE(q->state != (mode & TASK_NORMAL));
> + }
> +#endif
Yes, perhaps...
Actually, I think that TASK_NORMAL should be used even if wq mixes
UNINTERRUPTIBLE and KILLABLE waiters. The fact that TASK_KILLABLE
includes TASK_UNINTERRUPTIBLE is just "implementation detail" even
if I do not think this will be ever changed.
Oleg.
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[PATCH 0/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Oleg Nesterov <oleg@redhat.com> - 2016-08-26 15:00 +0200
[PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Oleg Nesterov <oleg@redhat.com> - 2016-08-26 15:00 +0200
Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Peter Zijlstra <peterz@infradead.org> - 2016-09-01 23:10 +0200
Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Oleg Nesterov <oleg@redhat.com> - 2016-09-02 14:10 +0200
Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Peter Zijlstra <peterz@infradead.org> - 2016-09-01 23:20 +0200
Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Peter Zijlstra <peterz@infradead.org> - 2016-09-02 00:20 +0200
Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Oleg Nesterov <oleg@redhat.com> - 2016-09-02 14:10 +0200
Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Peter Zijlstra <peterz@infradead.org> - 2016-09-02 15:30 +0200
Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Oleg Nesterov <oleg@redhat.com> - 2016-09-02 14:10 +0200
[PATCH 1/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Oleg Nesterov <oleg@redhat.com> - 2016-08-26 15:00 +0200
Re: [PATCH 1/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Peter Zijlstra <peterz@infradead.org> - 2016-09-01 13:40 +0200
Re: [PATCH 1/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Oleg Nesterov <oleg@redhat.com> - 2016-09-01 23:10 +0200
Re: [PATCH 1/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Peter Zijlstra <peterz@infradead.org> - 2016-09-02 00:50 +0200
Re: [PATCH 0/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Peter Zijlstra <peterz@infradead.org> - 2016-09-01 13:10 +0200
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