[PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Viresh Kumar]

In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
zero.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq_stats.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 2fd779e..bfd6273 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -180,15 +180,19 @@ static void cpufreq_stats_free_sysfs(unsigned int cpu)
 {
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 
-	if (!cpufreq_frequency_get_table(cpu))
+	if (!policy)
 		return;
 
-	if (policy && !policy_is_shared(policy)) {
+	if (!cpufreq_frequency_get_table(cpu))
+		goto put_ref;
+
+	if (!policy_is_shared(policy)) {
 		pr_debug("%s: Free sysfs stat\n", __func__);
 		sysfs_remove_group(&policy->kobj, &stats_attr_group);
 	}
-	if (policy)
-		cpufreq_cpu_put(policy);
+
+put_ref:
+	cpufreq_cpu_put(policy);
 }
 
 static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
-- 
1.7.12.rc2.18.g61b472e

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Amit Kucheria]

On Fri, Mar 22, 2013 at 3:43 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
> with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
> zero.

Rafael,

Since this prevents booting on our hardware (we unregister and
re-register the cpufreq driver to account for virtual cores), will
this be considered as a hotfix for 3.9?

> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Acked-by: Amit Kucheria <amit.kucheria@linaro.org>

> ---
>  drivers/cpufreq/cpufreq_stats.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
> index 2fd779e..bfd6273 100644
> --- a/drivers/cpufreq/cpufreq_stats.c
> +++ b/drivers/cpufreq/cpufreq_stats.c
> @@ -180,15 +180,19 @@ static void cpufreq_stats_free_sysfs(unsigned int cpu)
>  {
>         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
>
> -       if (!cpufreq_frequency_get_table(cpu))
> +       if (!policy)
>                 return;
>
> -       if (policy && !policy_is_shared(policy)) {
> +       if (!cpufreq_frequency_get_table(cpu))
> +               goto put_ref;
> +
> +       if (!policy_is_shared(policy)) {
>                 pr_debug("%s: Free sysfs stat\n", __func__);
>                 sysfs_remove_group(&policy->kobj, &stats_attr_group);
>         }
> -       if (policy)
> -               cpufreq_cpu_put(policy);
> +
> +put_ref:
> +       cpufreq_cpu_put(policy);
>  }
>
>  static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
> --
> 1.7.12.rc2.18.g61b472e
>

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Viresh Kumar]

On 22 March 2013 16:42, Amit Kucheria <amit.kucheria@linaro.org> wrote:
> On Fri, Mar 22, 2013 at 3:43 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>> In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
>> with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
>> zero.
>
> Rafael,
>
> Since this prevents booting on our hardware (we unregister and
> re-register the cpufreq driver to account for virtual cores), will
> this be considered as a hotfix for 3.9?
>
>> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
>
> Acked-by: Amit Kucheria <amit.kucheria@linaro.org>

Sorry i forgot to mention, this should be pushed for next rc.

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Rafael J. Wysocki]

On Friday, March 22, 2013 04:47:29 PM Viresh Kumar wrote:
> On 22 March 2013 16:42, Amit Kucheria <amit.kucheria@linaro.org> wrote:
> > On Fri, Mar 22, 2013 at 3:43 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> >> In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
> >> with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
> >> zero.
> >
> > Rafael,
> >
> > Since this prevents booting on our hardware (we unregister and
> > re-register the cpufreq driver to account for virtual cores), will
> > this be considered as a hotfix for 3.9?
> >
> >> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> >
> > Acked-by: Amit Kucheria <amit.kucheria@linaro.org>
> 
> Sorry i forgot to mention, this should be pushed for next rc.

Well, -rc5 is a realistic target.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Rafael J. Wysocki]

On Friday, March 22, 2013 04:42:57 PM Amit Kucheria wrote:
> On Fri, Mar 22, 2013 at 3:43 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
> > with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
> > zero.
> 
> Rafael,
> 
> Since this prevents booting on our hardware (we unregister and
> re-register the cpufreq driver to account for virtual cores), will
> this be considered as a hotfix for 3.9?

Sure.  Can you please remind me what hardware is that, though?

Rafael


> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> 
> Acked-by: Amit Kucheria <amit.kucheria@linaro.org>
> 
> > ---
> >  drivers/cpufreq/cpufreq_stats.c | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
> > index 2fd779e..bfd6273 100644
> > --- a/drivers/cpufreq/cpufreq_stats.c
> > +++ b/drivers/cpufreq/cpufreq_stats.c
> > @@ -180,15 +180,19 @@ static void cpufreq_stats_free_sysfs(unsigned int cpu)
> >  {
> >         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> >
> > -       if (!cpufreq_frequency_get_table(cpu))
> > +       if (!policy)
> >                 return;
> >
> > -       if (policy && !policy_is_shared(policy)) {
> > +       if (!cpufreq_frequency_get_table(cpu))
> > +               goto put_ref;
> > +
> > +       if (!policy_is_shared(policy)) {
> >                 pr_debug("%s: Free sysfs stat\n", __func__);
> >                 sysfs_remove_group(&policy->kobj, &stats_attr_group);
> >         }
> > -       if (policy)
> > -               cpufreq_cpu_put(policy);
> > +
> > +put_ref:
> > +       cpufreq_cpu_put(policy);
> >  }
> >
> >  static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
> > --
> > 1.7.12.rc2.18.g61b472e
> >
> --
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Viresh Kumar]

On 22 March 2013 17:29, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> Sure.  Can you please remind me what hardware is that, though?

Not yet upstreamed: big LITTLE :)

But, this is broken for all other platforms too.. You just need to compile
your driver as module and insmod/remove it to call
cpufreq_driver_unregister().

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Amit Kucheria]

On Fri, Mar 22, 2013 at 5:25 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 22 March 2013 17:29, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> Sure.  Can you please remind me what hardware is that, though?
>
> Not yet upstreamed: big LITTLE :)

Yes, the b.L cpufreq driver is being reviewed currently. And board
support is being merged in.

> But, this is broken for all other platforms too.. You just need to compile
> your driver as module and insmod/remove it to call
> cpufreq_driver_unregister().

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Rafael J. Wysocki]

On Friday, March 22, 2013 05:25:13 PM Viresh Kumar wrote:
> On 22 March 2013 17:29, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > Sure.  Can you please remind me what hardware is that, though?
> 
> Not yet upstreamed: big LITTLE :)
> 
> But, this is broken for all other platforms too.. You just need to compile
> your driver as module and insmod/remove it to call
> cpufreq_driver_unregister().

Which would be useful to write in the changelog, wouldn't it?

Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Viresh Kumar]

[-- Attachment #1: Type: text/plain, Size: 1007 bytes --]

On 22 March 2013 17:42, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> Which would be useful to write in the changelog, wouldn't it?

Hmm..

copy-paste with gmail is also broken, so find it attached too.

New change log, no change in patch and you can trust me on that :)

----------x-------------x--------

>From 034e5ac4cccd09872592a46decd38d5f24047f10 Mon Sep 17 00:00:00 2001
Message-Id: <034e5ac4cccd09872592a46decd38d5f24047f10.1363954124.git.viresh.kumar@linaro.org>
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: Fri, 22 Mar 2013 15:15:48 +0530
Subject: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to
 cpufreq_cpu_get

In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
zero.

We will get a hang if somehow cpufreq_driver_unregister() is called. And that
can happen when we compile our driver as module and insmod/rmmod it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

[-- Attachment #2: 0001-cpufreq-stats-do-cpufreq_cpu_put-corresponding-to-cp.patch --]
[-- Type: application/octet-stream, Size: 1634 bytes --]

From 034e5ac4cccd09872592a46decd38d5f24047f10 Mon Sep 17 00:00:00 2001
Message-Id: <034e5ac4cccd09872592a46decd38d5f24047f10.1363954124.git.viresh.kumar@linaro.org>
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: Fri, 22 Mar 2013 15:15:48 +0530
Subject: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to
 cpufreq_cpu_get

In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
zero.

We will get a hang if somehow cpufreq_driver_unregister() is called. And that
can happen when we compile our driver as module and insmod/rmmod it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq_stats.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 2fd779e..bfd6273 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -180,15 +180,19 @@ static void cpufreq_stats_free_sysfs(unsigned int cpu)
 {
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 
-	if (!cpufreq_frequency_get_table(cpu))
+	if (!policy)
 		return;
 
-	if (policy && !policy_is_shared(policy)) {
+	if (!cpufreq_frequency_get_table(cpu))
+		goto put_ref;
+
+	if (!policy_is_shared(policy)) {
 		pr_debug("%s: Free sysfs stat\n", __func__);
 		sysfs_remove_group(&policy->kobj, &stats_attr_group);
 	}
-	if (policy)
-		cpufreq_cpu_put(policy);
+
+put_ref:
+	cpufreq_cpu_put(policy);
 }
 
 static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
-- 
1.7.12.rc2.18.g61b472e

Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

[Rafael J. Wysocki]

On Friday, March 22, 2013 05:40:25 PM Viresh Kumar wrote:
> On 22 March 2013 17:42, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > Which would be useful to write in the changelog, wouldn't it?
> 
> Hmm..
> 
> copy-paste with gmail is also broken, so find it attached too.
> 
> New change log, no change in patch and you can trust me on that :)

OK, applied to bleeding-edge.

Thanks,
Rafael


> ----------x-------------x--------
> 
> From 034e5ac4cccd09872592a46decd38d5f24047f10 Mon Sep 17 00:00:00 2001
> Message-Id: <034e5ac4cccd09872592a46decd38d5f24047f10.1363954124.git.viresh.kumar@linaro.org>
> From: Viresh Kumar <viresh.kumar@linaro.org>
> Date: Fri, 22 Mar 2013 15:15:48 +0530
> Subject: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to
>  cpufreq_cpu_get
> 
> In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
> with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
> zero.
> 
> We will get a hang if somehow cpufreq_driver_unregister() is called. And that
> can happen when we compile our driver as module and insmod/rmmod it.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.