Re: [PATCH] PM / OPP: Call notifier without holding opp_table->lock

From	Stephen Boyd <sboyd@codeaurora.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] PM / OPP: Call notifier without holding opp_table->lock
Date	2017-09-20 21:50 +0200
Message-ID	<urTar-7oz-13@gated-at.bofh.it> (permalink)
References	<urPgu-4TY-31@gated-at.bofh.it> <urPgu-4TY-29@gated-at.bofh.it> <urQFA-5Wh-33@gated-at.bofh.it> <urQFA-5Wh-31@gated-at.bofh.it>
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On 09/20, Viresh Kumar wrote:
> On 20-09-17, 10:00, Stephen Boyd wrote:
> > On 09/20, Viresh Kumar wrote:
> 
> > > diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
> > > index 4360b4efcd4c..668fd940d362 100644
> > > --- a/drivers/base/power/opp/core.c
> > > +++ b/drivers/base/power/opp/core.c
> > > @@ -1627,6 +1627,9 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
> > >  
> > >  	opp->available = availability_req;
> > >  
> > > +	dev_pm_opp_get(opp);
> > > +	mutex_unlock(&opp_table->lock);
> > 
> > Does this prevent the OPP from changing while the lock is
> > released?
> 
> No, its just ref counting and will only prevent it from getting freed.
> 
> There is only one thing that can change for an OPP though after it is
> created, its availability.

Ok.

> 
> > That would be the only difference from before. It's
> > possible that nobody cares about this situation though.
> 
> I am not sure if its worth caring for right now :)
> 
> Also the notifier chain will not start again until the previous call
> chain is finished. So we are kind of synchronized here.
> 

Yep. Just me worrying out loud. You can add my

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>

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Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Thread

[PATCH] PM / OPP: Call notifier without holding opp_table->lock Viresh Kumar <viresh.kumar@linaro.org> - 2017-09-20 17:40 +0200
  Re: [PATCH] PM / OPP: Call notifier without holding opp_table->lock Viresh Kumar <viresh.kumar@linaro.org> - 2017-09-20 19:10 +0200
    Re: [PATCH] PM / OPP: Call notifier without holding opp_table->lock Stephen Boyd <sboyd@codeaurora.org> - 2017-09-20 21:50 +0200
  Re: [PATCH] PM / OPP: Call notifier without holding opp_table->lock Stephen Boyd <sboyd@codeaurora.org> - 2017-09-20 19:10 +0200

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