diff mbox

cpufreq: Avoid unnecessary locking in show() and store()

Message ID 15659367.8so4AOBv9e@vostro.rjw.lan (mailing list archive)
State Accepted, archived
Delegated to: Rafael Wysocki
Headers show

Commit Message

Rafael J. Wysocki Feb. 12, 2016, 4:10 p.m. UTC 
On Friday, February 12, 2016 09:28:29 PM Viresh Kumar wrote:
> On 12-02-16, 14:18, Rafael J. Wysocki wrote:
> > Well, having a check that never fails is certainly unuseful.
> > 
> > > So, even we may want to add a WARN_ON() for that case instead.
> > 
> > I can add WARN_ON()s just fine.
> 
> What about dropping the check completely ?

Fine by me.

---
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Subject: [PATCH] cpufreq: Drop unnecessary checks from show() and store()

The show() and store() routines in the cpufreq core don't need to
check if the struct freq_attr they want to use really provides the
callbacks they need as expected (if that's not the case, it means
a bug in the code anyway), so change them to avoid doing that.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpufreq/cpufreq.c |   21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)


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Comments

Viresh Kumar Feb. 12, 2016, 4:20 p.m. UTC | #1 
On 12-02-16, 17:10, Rafael J. Wysocki wrote:
> On Friday, February 12, 2016 09:28:29 PM Viresh Kumar wrote:
> > On 12-02-16, 14:18, Rafael J. Wysocki wrote:
> > > Well, having a check that never fails is certainly unuseful.
> > > 
> > > > So, even we may want to add a WARN_ON() for that case instead.
> > > 
> > > I can add WARN_ON()s just fine.
> > 
> > What about dropping the check completely ?
> 
> Fine by me.
> 
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Subject: [PATCH] cpufreq: Drop unnecessary checks from show() and store()
> 
> The show() and store() routines in the cpufreq core don't need to
> check if the struct freq_attr they want to use really provides the
> callbacks they need as expected (if that's not the case, it means
> a bug in the code anyway), so change them to avoid doing that.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/cpufreq/cpufreq.c |   21 +++++----------------
>  1 file changed, 5 insertions(+), 16 deletions(-)

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
diff mbox

Patch

Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -863,12 +863,7 @@  static ssize_t show(struct kobject *kobj
 	ssize_t ret;
 
 	down_read(&policy->rwsem);
-
-	if (fattr->show)
-		ret = fattr->show(policy, buf);
-	else
-		ret = -EIO;
-
+	ret = fattr->show(policy, buf);
 	up_read(&policy->rwsem);
 
 	return ret;
@@ -883,18 +878,12 @@  static ssize_t store(struct kobject *kob
 
 	get_online_cpus();
 
-	if (!cpu_online(policy->cpu))
-		goto unlock;
-
-	down_write(&policy->rwsem);
-
-	if (fattr->store)
+	if (cpu_online(policy->cpu)) {
+		down_write(&policy->rwsem);
 		ret = fattr->store(policy, buf, count);
-	else
-		ret = -EIO;
+		up_write(&policy->rwsem);
+	}
 
-	up_write(&policy->rwsem);
-unlock:
 	put_online_cpus();
 
 	return ret;