From: Viresh Kumar <viresh.kumar@linaro.org>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: Rafael Wysocki <rjw@rjwysocki.net>,
cw00.choi@samsung.com, Viresh Kumar <vireshk@kernel.org>,
Nishanth Menon <nm@ti.com>,
linux-pm@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
myungjoo.ham@samsung.com, inki.dae@samsung.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] PM / OPP: Call notifier without holding opp_table->lock
Date: Wed, 20 Sep 2017 10:07:55 -0700 [thread overview]
Message-ID: <20170920170755.GA3001@ubuntu> (raw)
In-Reply-To: <20170920170000.GA457@codeaurora.org>
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.
> 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.
--
viresh
next prev parent reply other threads:[~2017-09-20 17:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20170920102206epcas1p2ae5b3a2020efa368f6c0640403695cbd@epcas1p2.samsung.com>
2017-09-20 10:22 ` OPP's mutex locking issue Chanwoo Choi
2017-09-20 15:34 ` [PATCH] PM / OPP: Call notifier without holding opp_table->lock Viresh Kumar
2017-09-20 17:00 ` Stephen Boyd
2017-09-20 17:07 ` Viresh Kumar [this message]
2017-09-20 19:47 ` Stephen Boyd
2017-09-20 20:25 ` [PATCH V2] " Viresh Kumar
2017-09-20 23:58 ` Chanwoo Choi
2017-09-21 17:44 ` [PATCH V3] " Viresh Kumar
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