Re: [patch 15/16] cpufreq: intel-pstate: Use del_timer_sync in intel_pstate_cpu_exit()

From: Dirk Brandewie <dirk.brandewie@gmail.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	dirk.j.brandewie@intel.com
Cc: dirk.brandewie@gmail.com, LKML <linux-kernel@vger.kernel.org>,
	Julia Lawall <Julia.Lawall@lip6.fr>,
	Andrew Morton <akpm@linux-foundation.org>,
	cpufreq <cpufreq@vger.kernel.org>, pm <linux-pm@vger.kernel.org>
Subject: Re: [patch 15/16] cpufreq: intel-pstate: Use del_timer_sync in intel_pstate_cpu_exit()
Date: Mon, 24 Mar 2014 07:18:01 -0700	[thread overview]
Message-ID: <53303E99.70509@gmail.com> (raw)
In-Reply-To: <2311758.L3eN8OTkba@vostro.rjw.lan>

Hi Thomas,
On 03/23/2014 06:56 PM, Rafael J. Wysocki wrote:
> On Sunday, March 23, 2014 03:09:32 PM Thomas Gleixner wrote:
>> We are about to free the data structure. Make sure no timer callback
>> is running. I might be paranoid, but the ->exit callback can be
>> invoked from so many places, that it is not entirely clear whether
>> del_timer is always called on the cpu on which it is enqueued.
>>
>> While looking through the call sites I noticed, that
>> cpufreq_init_policy() can fail and invoke cpufreq_driver->exit() but
>> it does not return the failure and the callsite happily proceeds.
>>

The call to del_timer() has been moved to a new callback in material
in Rafaels pull request for v3.15.

I will send a patch adding this change to the v3.15 material.

--Dirk
>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
>> Cc: cpufreq <cpufreq@vger.kernel.org>
>> Cc: pm <linux-pm@vger.kernel.org>
>
> Dirk?
>
>> ---
>>
>>   drivers/cpufreq/intel_pstate.c |    2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Index: tip/drivers/cpufreq/intel_pstate.c
>> ===================================================================
>> --- tip.orig/drivers/cpufreq/intel_pstate.c
>> +++ tip/drivers/cpufreq/intel_pstate.c
>> @@ -777,7 +777,7 @@ static int intel_pstate_cpu_exit(struct
>>   {
>>   	int cpu = policy->cpu;
>>
>> -	del_timer(&all_cpu_data[cpu]->timer);
>> +	del_timer_sync(&all_cpu_data[cpu]->timer);
>>   	kfree(all_cpu_data[cpu]);
>>   	all_cpu_data[cpu] = NULL;
>>   	return 0;
>>
>>
>