diff mbox

[RFC,12/19] cpufreq: fix locking of policy->rwsem in cpufreq_init_policy

Message ID 1452533760-13787-13-git-send-email-juri.lelli@arm.com (mailing list archive)
State RFC
Headers show

Commit Message

Juri Lelli Jan. 11, 2016, 5:35 p.m. UTC
There are paths in cpufreq_init_policy where policy is used, but its rwsem
is not held.

Fix it.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
---
 drivers/cpufreq/cpufreq.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

Comments

Viresh Kumar Jan. 12, 2016, 10:39 a.m. UTC | #1
On 11-01-16, 17:35, Juri Lelli wrote:
> There are paths in cpufreq_init_policy where policy is used, but its rwsem
> is not held.
> 
> Fix it.
> 
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Signed-off-by: Juri Lelli <juri.lelli@arm.com>
> ---
>  drivers/cpufreq/cpufreq.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index e7fc5c9..2c7cc6c73 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -998,21 +998,24 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
>  {
>  	int ret = 0;
>  
> +	down_write(&policy->rwsem);
> +
>  	/* Has this CPU been taken care of already? */
> -	if (cpumask_test_cpu(cpu, policy->cpus))
> +	if (cpumask_test_cpu(cpu, policy->cpus)) {
> +		up_write(&policy->rwsem);

Perhaps create a label at the end to unlock the rwsem and jump to it?
Juri Lelli Jan. 14, 2016, 5:58 p.m. UTC | #2
On 12/01/16 16:09, Viresh Kumar wrote:
> On 11-01-16, 17:35, Juri Lelli wrote:
> > There are paths in cpufreq_init_policy where policy is used, but its rwsem
> > is not held.
> > 
> > Fix it.
> > 
> > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> > Cc: Viresh Kumar <viresh.kumar@linaro.org>
> > Signed-off-by: Juri Lelli <juri.lelli@arm.com>
> > ---
> >  drivers/cpufreq/cpufreq.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index e7fc5c9..2c7cc6c73 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -998,21 +998,24 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
> >  {
> >  	int ret = 0;
> >  
> > +	down_write(&policy->rwsem);
> > +
> >  	/* Has this CPU been taken care of already? */
> > -	if (cpumask_test_cpu(cpu, policy->cpus))
> > +	if (cpumask_test_cpu(cpu, policy->cpus)) {
> > +		up_write(&policy->rwsem);
> 
> Perhaps create a label at the end to unlock the rwsem and jump to it?
> 

Yep, done.

Thanks,

- Juri
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diff mbox

Patch

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e7fc5c9..2c7cc6c73 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -998,21 +998,24 @@  static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
 {
 	int ret = 0;
 
+	down_write(&policy->rwsem);
+
 	/* Has this CPU been taken care of already? */
-	if (cpumask_test_cpu(cpu, policy->cpus))
+	if (cpumask_test_cpu(cpu, policy->cpus)) {
+		up_write(&policy->rwsem);
 		return 0;
+	}
 
 	if (has_target()) {
 		ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
 		if (ret) {
+			up_write(&policy->rwsem);
 			pr_err("%s: Failed to stop governor\n", __func__);
 			return ret;
 		}
 	}
 
-	down_write(&policy->rwsem);
 	cpumask_set_cpu(cpu, policy->cpus);
-	up_write(&policy->rwsem);
 
 	if (has_target()) {
 		ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
@@ -1020,10 +1023,12 @@  static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
 			ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
 
 		if (ret) {
+			up_write(&policy->rwsem);
 			pr_err("%s: Failed to start governor\n", __func__);
 			return ret;
 		}
 	}
+	up_write(&policy->rwsem);
 
 	return 0;
 }