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 5.4-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-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cd0b768b1aef6c56bd43bd43fc1fedbfbd026a56
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 549788a2a9676..e727282f56963 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1639,19 +1639,26 @@ 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);
}
/**
