All of lore.kernel.org
 help / color / mirror / Atom feed
From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rafael@kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org,
	Vincent Guittot <vincent.guittot@linaro.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 3/3] cpufreq: Drop unnecessary cpus locking from store()
Date: Thu, 26 May 2022 17:21:21 +0530	[thread overview]
Message-ID: <0a6620ff5a330126b21d00244d4fad62cff4f230.1653565641.git.viresh.kumar@linaro.org> (raw)
In-Reply-To: <cover.1653565641.git.viresh.kumar@linaro.org>

This change was introduced long back by:

commit 4f750c930822 ("cpufreq: Synchronize the cpufreq store_*() routines with CPU hotplug")

Since then, both cpufreq and hotplug core have been reworked and have
much better locking in place. The race mentioned in commit 4f750c930822
isn't possible anymore.

Drop the unnecessary locking.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 53d163a84e06..bb237d1ce5e7 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -973,21 +973,10 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
 	if (!fattr->store)
 		return -EIO;
 
-	/*
-	 * cpus_read_trylock() is used here to work around a circular lock
-	 * dependency problem with respect to the cpufreq_register_driver().
-	 */
-	if (!cpus_read_trylock())
-		return -EBUSY;
-
-	if (cpu_online(policy->cpu)) {
-		down_write(&policy->rwsem);
-		if (likely(!policy_is_inactive(policy)))
-			ret = fattr->store(policy, buf, count);
-		up_write(&policy->rwsem);
-	}
-
-	cpus_read_unlock();
+	down_write(&policy->rwsem);
+	if (likely(!policy_is_inactive(policy)))
+		ret = fattr->store(policy, buf, count);
+	up_write(&policy->rwsem);
 
 	return ret;
 }
-- 
2.31.1.272.g89b43f80a514


  parent reply	other threads:[~2022-05-26 11:52 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-26 11:51 [PATCH 0/3] cpufreq: Minor cleanups Viresh Kumar
2022-05-26 11:51 ` [PATCH 1/3] cpufreq: Optimize cpufreq_show_cpus() Viresh Kumar
2022-05-26 11:51 ` [PATCH 2/3] cpufreq: Panic if policy is active in cpufreq_policy_free() Viresh Kumar
2022-05-27  3:13   ` [cpufreq] a6cb305191: kernel_BUG_at_drivers/cpufreq/cpufreq.c kernel test robot
2022-05-27  3:13     ` kernel test robot
2022-05-27  3:54     ` Viresh Kumar
2022-05-27  3:54       ` Viresh Kumar
2022-05-27  3:53   ` [PATCH V2 2/3] cpufreq: Panic if policy is active in cpufreq_policy_free() Viresh Kumar
2022-06-14 13:59     ` Rafael J. Wysocki
2022-06-15  4:59       ` Viresh Kumar
2022-07-06 13:49         ` Rafael J. Wysocki
2022-07-06 15:23           ` Viresh Kumar
2022-07-06 15:34             ` Rafael J. Wysocki
2022-05-26 11:51 ` Viresh Kumar [this message]
2022-06-14 13:51   ` [PATCH 3/3] cpufreq: Drop unnecessary cpus locking from store() Rafael J. Wysocki

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=0a6620ff5a330126b21d00244d4fad62cff4f230.1653565641.git.viresh.kumar@linaro.org \
    --to=viresh.kumar@linaro.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=rafael@kernel.org \
    --cc=vincent.guittot@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.