[RFC PATCH 14/19] cpufreq: fix locking of policy->rwsem in cpufreq_offline_finish

[Juri Lelli]

There are paths in cpufreq_offline_prepare where policy is used, but its
rwsem is not held.

Fix it.

Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Signed-off-by: Juri Lelli <juri.lelli@xxxxxxx>
---
 drivers/cpufreq/cpufreq.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 91158b0..ba452c3 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1381,9 +1381,13 @@ static void cpufreq_offline_finish(unsigned int cpu)
 		return;
 	}
 
+	down_write(&policy->rwsem);
+
 	/* Only proceed for inactive policies */
-	if (!policy_is_inactive(policy))
+	if (!policy_is_inactive(policy)) {
+		up_write(&policy->rwsem);
 		return;
+	}
 
 	/* If cpu is last user of policy, free policy */
 	if (has_target()) {
@@ -1392,6 +1396,8 @@ static void cpufreq_offline_finish(unsigned int cpu)
 			pr_err("%s: Failed to exit governor\n", __func__);
 	}
 
+	up_write(&policy->rwsem);
+
 	/*
 	 * Perform the ->exit() even during light-weight tear-down,
 	 * since this is a core component, and is essential for the
-- 
2.2.2