Messages in this thread | | | Date | Thu, 8 Sep 2011 10:05:30 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH 1/1] freezer: fix wait_event_freezable/__thaw_task races |
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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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