Re: [tip:sched/core] sched/wait: Reimplement wait_event_freezable()

From: Pavel Machek
Date: Tue Nov 04 2014 - 15:12:11 EST


Hi!

> Commit-ID: 36df04bc5273a046f53b5e359febc1225f85aa7b
> Gitweb: http://git.kernel.org/tip/36df04bc5273a046f53b5e359febc1225f85aa7b
> Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> AuthorDate: Wed, 29 Oct 2014 12:21:57 +0100
> Committer: Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Tue, 4 Nov 2014 07:17:45 +0100
>
> sched/wait: Reimplement wait_event_freezable()
>
> Provide better implementations of wait_event_freezable() APIs.
>
> The problem is with freezer_do_not_count(), it hides the thread from
> the freezer, even though this thread might not actually freeze/sleep
> at all.

Can you elaborate?

The thread will be in freezer_do_not_count() area, but it is just
waiting for event there, it should not do much damage.

If this is bugfix, should it be cc-ed to stable?

Did you test it with suspend/hibernation? Because I can't really see
how it works.

> +#define __wait_event_freezable(wq, condition) \
> + ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0, \
> + schedule(); try_to_freeze())
> +

_Three_ underscores. And two underscore version exists, too,
fortunately it at least has different number of arguments.
Pavel
--
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