linux-kernel - Re: [PATCH pm] freezer: fix wait_event_freezable/__thaw

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Message-ID: <20111103004350.GA4417@google.com>
Date:	Wed, 2 Nov 2011 17:43:50 -0700
From:	Tejun Heo <tj@...nel.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-kernel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
	linux-pm@...r.kernel.org
Subject: Re: [PATCH pm] freezer: fix wait_event_freezable/__thaw_task races

On Thu, Nov 03, 2011 at 01:20:41AM +0100, Rafael J. Wysocki wrote:
> On Tuesday, November 01, 2011, Tejun Heo wrote:
> > From: Oleg Nesterov <oleg@...hat.com>
> > 
> > wait_event_freezable() and friends 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
> > 
> > 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.
> > 
> > tj: Updated to apply to wait_event_freezekillable() too.
> > 
> > Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> > Acked-by: Tejun Heo <tj@...nel.org>
> 
> Applied to linux-pm/linux-next.

Just in case, this patch isn't correct with preceding patches (the
freezer update patchset), so should only be applied after them.

Thanks.

-- 
tejun
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