linux-kernel - Re: [PATCH 1/2] PM / wakeup: Remove timer from wakeup_source

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Date:   Tue, 12 Mar 2019 08:58:02 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        sunzhaosheng@...ilicon.com, jean.xupeng@...ilicon.com,
        yuwei3@...ilicon.com, gengyanping@...ilicon.com,
        peter.panshilin@...ilicon.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] PM / wakeup: Remove timer from wakeup_source_remove()

On 11-03-19, 13:05, Rafael J. Wysocki wrote:
> On Friday, March 8, 2019 10:53:11 AM CET Viresh Kumar wrote:
> > wakeup_source_remove() is the counterpart of wakeup_source_add() helper
> > and must undo the initializations done by wakeup_source_add(). Currently
> > the timer is initialized by wakeup_source_add() but removed from
> > wakeup_source_drop(), which doesn't look logically correct. Also it
> > should be okay to call wakeup_source_add() right after calling
> > wakeup_source_remove(), and in that case we may end up calling
> > timer_setup() for a potentially scheduled timer which is surely
> > incorrect.
> > 
> > Move the timer removal part to wakeup_source_remove() instead.
> > 
> > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > ---
> >  drivers/base/power/wakeup.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
> > index f1fee72ed970..18333962e3da 100644
> > --- a/drivers/base/power/wakeup.c
> > +++ b/drivers/base/power/wakeup.c
> > @@ -118,7 +118,6 @@ void wakeup_source_drop(struct wakeup_source *ws)
> >  	if (!ws)
> >  		return;
> >  
> > -	del_timer_sync(&ws->timer);
> >  	__pm_relax(ws);
> >  }
> >  EXPORT_SYMBOL_GPL(wakeup_source_drop);
> > @@ -205,6 +204,8 @@ void wakeup_source_remove(struct wakeup_source *ws)
> >  	list_del_rcu(&ws->entry);
> >  	raw_spin_unlock_irqrestore(&events_lock, flags);
> >  	synchronize_srcu(&wakeup_srcu);
> > +
> > +	del_timer_sync(&ws->timer);
> >  }
> >  EXPORT_SYMBOL_GPL(wakeup_source_remove);
> >  
> > 
> 
> I've merged it with the [2/2], rewritten the subject and changelog and
> queued the result as commit d856f39ac1cc ("PM / wakeup: Rework wakeup
> source timer cancellation").

Okay, thanks. We (Android guys) want this to be backported into 4.4+
kernels via the stable tree. Can we mark this for stable in the commit
itself ? Else I would be required to send this separately for all the
kernels. I should have marked it for stable initially though, sorry
about forgetting then.

-- 
viresh