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SubjectRe: [PATCH 1/1] freezer: fix wait_event_freezable/__thaw_task races
Hello,

On Wed, Sep 07, 2011 at 08:22:17PM +0200, Oleg Nesterov wrote:
> wait_event_freezable() and wait_event_freezable_timeout() stop
> the waiting if try_to_freeze() fails. This is not right, we can
> race with __thaw_task() and in this case
>
> - wait_event_freezable() returns the wrong ERESTARTSYS
>
> - wait_event_freezable_timeout() can return the positive
> value while condition == F

Indeed, nice catch. This one actually is pretty dangerous. We
probably want to make a separate fix for this and backport it to
-stable?

> Change the code to always check __retval/condition before return.
>
> Note: with or without this patch the timeout logic looks strange,
> probably we should recalc timeout if try_to_freeze() returns T.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Yeap, with freezable_with_signal gone, this looks correct & simpler to
me but it would be nice if you can sprinkle some documentation while
at it. :)

Thanks.

--
tejun


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