From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linux PM list <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cpufreq: Avoid unnecessary locking in show() and store()
Date: Fri, 12 Feb 2016 17:10:09 +0100 [thread overview]
Message-ID: <15659367.8so4AOBv9e@vostro.rjw.lan> (raw)
In-Reply-To: <20160212155829.GA32705@vireshk-i7>
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(-)
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;
next prev parent reply other threads:[~2016-02-12 16:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-11 1:25 [PATCH] cpufreq: Avoid unnecessary locking in show() and store() Rafael J. Wysocki
2016-02-12 6:31 ` Viresh Kumar
2016-02-12 13:18 ` Rafael J. Wysocki
2016-02-12 15:58 ` Viresh Kumar
2016-02-12 16:10 ` Rafael J. Wysocki [this message]
2016-02-12 16:20 ` Viresh Kumar
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