linux-kernel - Re: linux-next: Tree for Feb 8 [ smp|cpufreq: WARNING: at kernel/smp.c:245 smp_call_function

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Date:	Fri, 8 Feb 2013 16:19:33 +0100
From:	Sedat Dilek <sedat.dilek@...il.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, Hillf Danton <dhillf@...il.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next@...r.kernel.org, linux-kernel@...r.kernel.org,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	Linux PM List <linux-pm@...ts.linux-foundation.org>,
	x86@...nel.org, Ingo Molnar <mingo@...hat.com>,
	Chuansheng Liu <chuansheng.liu@...el.com>
Subject: Re: linux-next: Tree for Feb 8 [ smp|cpufreq: WARNING: at
 kernel/smp.c:245 smp_call_function_single ]

On Fri, Feb 8, 2013 at 3:50 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> On Fri, Feb 8, 2013 at 7:45 PM, Sedat Dilek <sedat.dilek@...il.com> wrote:
>> "...some...changes..." is not very concrete :-).
>> Which commit(s) caused this trouble?
>>
>> Is current (meanwhile updated?) linux-pm.git#linux-next good (didn't
>> check last commit-ids of your tree from Next/ dir)?
>
> Attached patch would fix it for you and it looks like and is going to be
> pulled in by Rafael:
>
> From: Viresh Kumar <viresh.kumar@...aro.org>
> Date: Fri, 8 Feb 2013 10:35:31 +0530
> Subject: [PATCH] cpufreq: Remove unnecessary locking
>
> I have placed some locks intentionally around calls to driver->ops (init/exit),
> which look to be wrong as these calls can call routines that potentially sleep.
>
> Lets remove these locks.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>

Tested-by: Sedat Dilek <sedat.dilek@...il.com>

( 0001-cpufreq-Remove-unnecessary-locking.patch fixes the issue here! )

- Sedat -

> ---
>  drivers/cpufreq/cpufreq.c | 7 -------
>  1 file changed, 7 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 5d8a422..04aab05 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -795,10 +795,8 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
>
>         if (ret) {
>                 pr_debug("setting policy failed\n");
> -               spin_lock_irqsave(&cpufreq_driver_lock, flags);
>                 if (driver->exit)
>                         driver->exit(policy);
> -               spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
>         }
>         return ret;
>
> @@ -920,17 +918,14 @@ static int cpufreq_add_dev(struct device *dev,
> struct subsys_interface *sif)
>         init_completion(&policy->kobj_unregister);
>         INIT_WORK(&policy->update, handle_update);
>
> -       spin_lock_irqsave(&cpufreq_driver_lock, flags);
>         /* call driver. From then on the cpufreq must be able
>          * to accept all calls to ->verify and ->setpolicy for this CPU
>          */
>         ret = driver->init(policy);
>         if (ret) {
>                 pr_debug("initialization failed\n");
> -               spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
>                 goto err_set_policy_cpu;
>         }
> -       spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
>
>         /* related cpus should atleast have policy->cpus */
>         cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);
> @@ -1100,10 +1095,8 @@ static int __cpufreq_remove_dev(struct device
> *dev, struct subsys_interface *sif
>                 wait_for_completion(cmp);
>                 pr_debug("wait complete\n");
>
> -               spin_lock_irqsave(&cpufreq_driver_lock, flags);
>                 if (driver->exit)
>                         driver->exit(data);
> -               spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
>
>                 free_cpumask_var(data->related_cpus);
>                 free_cpumask_var(data->cpus);
--
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