linux-kernel - Re: [PATCH] cpufreq: acpi: policy->driver

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Message-ID: <20160330112104.GF24343@vireshk-i7>
Date:	Wed, 30 Mar 2016 16:51:04 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Rafael Wysocki <rjw@...ysocki.net>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: acpi: policy->driver_data can't be NULL in
 ->exit()

On 30-03-16, 13:15, Rafael J. Wysocki wrote:
> On Wed, Mar 30, 2016 at 6:24 AM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> > Its always set by ->init() and so it will always be there in ->exit().
> > There is no need to have a special check for just that.
> 
> I'm not sure what happens if there are two (or more) CPUs in the policy, though.
> 
> That case is almost certainly handled incorrectly here (or rather not
> handled at all), but it may just happen to sort of work, because the
> first exiting CPU will clear driver_data and the second one will
> notice that it is NULL now.  Of course, that still is racy with
> respect to governors etc, but I'd rather fix the driver properly.

Sorry, I probably didn't understood your comments properly.

But, the core will call ->exit() only for the last exiting CPU. So,
driver_data will never be NULL.

-- 
viresh