linux-kernel - Re: [PATCH] opp: of: drop incorrect lockdep_assert

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Message-ID: <20191024025641.dknawrtzap4qwcm4@vireshk-i7>
Date:   Thu, 24 Oct 2019 08:26:41 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Niklas Cassel <niklas.cassel@...aro.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        "v5 . 0+" <stable@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] opp: of: drop incorrect lockdep_assert_held()

On 23-10-19, 14:01, Niklas Cassel wrote:
> On Wed, Oct 23, 2019 at 11:00:05AM +0530, Viresh Kumar wrote:
> > On 10-10-19, 16:00, Viresh Kumar wrote:
> > > _find_opp_of_np() doesn't traverse the list of OPP tables but instead
> > > just the entries within an OPP table and so only requires to lock the
> > > OPP table itself.
> > > 
> > > The lockdep_assert_held() was added there by mistake and isn't really
> > > required.
> > > 
> > > Fixes: 5d6d106fa455 ("OPP: Populate required opp tables from "required-opps" property")
> > > Cc: v5.0+ <stable@...r.kernel.org> # v5.0+
> > > Reported-by: Niklas Cassel <niklas.cassel@...aro.org>
> > > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > > ---
> > >  drivers/opp/of.c | 2 --
> > >  1 file changed, 2 deletions(-)
> > > 
> > > diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> > > index 1813f5ad5fa2..6dc41faf74b5 100644
> > > --- a/drivers/opp/of.c
> > > +++ b/drivers/opp/of.c
> > > @@ -77,8 +77,6 @@ static struct dev_pm_opp *_find_opp_of_np(struct opp_table *opp_table,
> > >  {
> > >  	struct dev_pm_opp *opp;
> > >  
> > > -	lockdep_assert_held(&opp_table_lock);
> > > -
> > >  	mutex_lock(&opp_table->lock);
> > >  
> > >  	list_for_each_entry(opp, &opp_table->opp_list, node) {
> > 
> > @Niklas, any inputs from your side  here would be appreciated :)
> 
> Tested-by: Niklas Cassel <niklas.cassel@...aro.org>
> 
> After this patch, there is still a single lockdep_assert_held()
> left, inside _find_table_of_opp_np(), since you kept this,
> I assume that that one is still needed?

Yeah, that one is required as we are traversing the list of OPP tables
there.

-- 
viresh