From 6895bcff6c3e35b6e3dba1122687a857cb8dc5fc Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Wed, 11 May 2022 17:51:39 +0200
Subject: [PATCH] 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@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Stable-dep-of: b8f85833c057 ("cpufreq: exit() callback is optional")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/cpufreq/cpufreq.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index bf7233cd1..43e662913 100755
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1661,19 +1661,26 @@ 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);
}
/**