linux-kernel - [PATCH 3.15 55/66] cpufreq: unlock when failing cpufreq_update

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Date:	Fri,  4 Jul 2014 15:14:54 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Aaron Plattner <aplattner@...dia.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 3.15 55/66] cpufreq: unlock when failing cpufreq_update_policy()

3.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Aaron Plattner <aplattner@...dia.com>

commit fefa8ff810c5ab4c4206aed9d159c4d6fe8d4f1c upstream.

Commit bd0fa9bb455d introduced a failure path to cpufreq_update_policy() if
cpufreq_driver->get(cpu) returns NULL.  However, it jumps to the 'no_policy'
label, which exits without unlocking any of the locks the function acquired
earlier.  This causes later calls into cpufreq to hang.

Fix this by creating a new 'unlock' label and jumping to that instead.

Fixes: bd0fa9bb455d ("cpufreq: Return error if ->get() failed in cpufreq_update_policy()")
Link: https://devtalk.nvidia.com/default/topic/751903/kernel-3-15-and-nv-drivers-337-340-failed-to-initialize-the-nvidia-kernel-module-gtx-550-ti-/
Signed-off-by: Aaron Plattner <aplattner@...dia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/cpufreq/cpufreq.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2166,10 +2166,8 @@ int cpufreq_update_policy(unsigned int c
 	struct cpufreq_policy new_policy;
 	int ret;

-	if (!policy) {
-		ret = -ENODEV;
-		goto no_policy;
-	}
+	if (!policy)
+		return -ENODEV;

 	down_write(&policy->rwsem);

@@ -2188,7 +2186,7 @@ int cpufreq_update_policy(unsigned int c
 		new_policy.cur = cpufreq_driver->get(cpu);
 		if (WARN_ON(!new_policy.cur)) {
 			ret = -EIO;
-			goto no_policy;
+			goto unlock;
 		}

 		if (!policy->cur) {
@@ -2203,10 +2201,10 @@ int cpufreq_update_policy(unsigned int c

 	ret = cpufreq_set_policy(policy, &new_policy);

+unlock:
 	up_write(&policy->rwsem);

 	cpufreq_cpu_put(policy);
-no_policy:
 	return ret;
 }
 EXPORT_SYMBOL(cpufreq_update_policy);

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