linux-kernel - Re: [PATCH] PM / QoS: Fix workqueue deadlock when using pm_qos_update_request

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Message-ID: <20130813204943.GH14845@codeaurora.org>
Date:	Tue, 13 Aug 2013 13:49:43 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PM / QoS: Fix workqueue deadlock when using
 pm_qos_update_request_timeout()

On 08/13, Rafael J. Wysocki wrote:
> On Tuesday, August 13, 2013 01:01:46 PM Tejun Heo wrote:
> > Hello,
> > 
> > On Tue, Aug 13, 2013 at 09:46:26AM -0700, Stephen Boyd wrote:
> > > >> +	if (PM_QOS_DEFAULT_VALUE != req->node.prio)
> > > >> +		pm_qos_update_target(
> > > >> +				pm_qos_array[req->pm_qos_class]->constraints,
> > > >> +				&req->node, PM_QOS_UPDATE_REQ,
> > > >> +				PM_QOS_DEFAULT_VALUE);
> > > > Maybe it'd be cleaner to add a param or internal variant of
> > > > pm_qos_update_request()?
> > > 
> > > Maybe, but I was trying to make a minimal fix here.
> > 
> > Hmmm.... it just looks like things can easily get out of sync with the
> > complex function call.
> 
> Yes, that's just duplicated code.
> 
> > I don't think it'll be too invasive if you introduce an internal variant
> > which doesn't do the canceling.  Rafael, what do you think?
> 
> I'd move the part of pm_qos_update_request() below the
> cancel_delayed_work_sync() to a separate static function that'd be
> called from two places.
> 

Ok I will throw this all into one patch and resend.

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