linux-kernel - Re: [PATCH 02/12] PM / OPP: Add 'struct kref' to OPP table

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Message-ID: <20170110042312.GB6332@vireshk-i7>
Date:   Tue, 10 Jan 2017 09:53:12 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Stephen Boyd <sboyd@...eaurora.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH 02/12] PM / OPP: Add 'struct kref' to OPP table

On 09-01-17, 15:36, Stephen Boyd wrote:
> On 12/07, Viresh Kumar wrote:
> > @@ -894,8 +895,36 @@ static void _kfree_device_rcu(struct rcu_head *head)
> >  	kfree_rcu(opp_table, rcu_head);
> >  }
> >  
> > -static void _free_opp_table(struct opp_table *opp_table)
> > +void _get_opp_table_kref(struct opp_table *opp_table)
> >  {
> > +	kref_get(&opp_table->kref);
> > +}
> > +
> > +struct opp_table *dev_pm_opp_get_opp_table(struct device *dev)
> > +{
> > +	struct opp_table *opp_table;
> > +
> > +	/* Hold our table modification lock here */
> > +	mutex_lock(&opp_table_lock);
> > +
> > +	opp_table = _find_opp_table(dev);
> > +	if (!IS_ERR(opp_table)) {
> > +		_get_opp_table_kref(opp_table);
> 
> It seems odd to have _get_opp_table_kref() take a pointer to
> increment a kref on.

This function is provided for better readability and passing opp_table to it is
the only option I had :)

> It would be better to have _find_opp_table()
> return the pointer with the reference already taken so that we
> don't have to update callers with reference grabbing calls.
> Typically if a function returns a reference counted pointer the
> reference counting has already been done.

Absolutely, but that happens with later patches in the series. I couldn't have
done it now, as something or the other would have broken.

-- 
viresh