Patch "cpufreq: Rearrange locking in cpufreq_remove_dev()" has been added to the 5.10-stable tree

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This is a note to let you know that I've just added the patch titled

    cpufreq: Rearrange locking in cpufreq_remove_dev()

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cpufreq-rearrange-locking-in-cpufreq_remove_dev.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 522edc42f14d84649533d149b362b2e8f9b61d4e
Author: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Date:   Wed May 11 17:51:39 2022 +0200

    cpufreq: Rearrange locking in cpufreq_remove_dev()
    
    [ Upstream commit f339f3541701d824a0256ad4bf14c26ceb6d79c3 ]
    
    Currently, cpufreq_remove_dev() invokes the ->exit() driver callback
    without holding the policy rwsem which is inconsistent with what
    happens if ->exit() is invoked directly from cpufreq_offline().
    
    It also manipulates the real_cpus mask and removes the CPU device
    symlink without holding the policy rwsem, but cpufreq_offline() holds
    the rwsem around the modifications thereof.
    
    For consistency, modify cpufreq_remove_dev() to hold the policy rwsem
    until the ->exit() callback has been called (or it has been determined
    that it is not necessary to call it).
    
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
    Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
    Stable-dep-of: b8f85833c057 ("cpufreq: exit() callback is optional")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index dd1acb55fe717..cbdea4fa600ab 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1645,19 +1645,26 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
 	if (!policy)
 		return;
 
+	down_write(&policy->rwsem);
+
 	if (cpu_online(cpu))
-		cpufreq_offline(cpu);
+		__cpufreq_offline(cpu, policy);
 
 	cpumask_clear_cpu(cpu, policy->real_cpus);
 	remove_cpu_dev_symlink(policy, dev);
 
-	if (cpumask_empty(policy->real_cpus)) {
-		/* We did light-weight exit earlier, do full tear down now */
-		if (cpufreq_driver->offline)
-			cpufreq_driver->exit(policy);
-
-		cpufreq_policy_free(policy);
+	if (!cpumask_empty(policy->real_cpus)) {
+		up_write(&policy->rwsem);
+		return;
 	}
+
+	/* We did light-weight exit earlier, do full tear down now */
+	if (cpufreq_driver->offline)
+		cpufreq_driver->exit(policy);
+
+	up_write(&policy->rwsem);
+
+	cpufreq_policy_free(policy);
 }
 
 /**




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