linux-kernel - [PATCH 4.6 57/96] cpufreq: Avoid false-positive WARN_ON()s in cpufreq_update

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Date:	Mon,  8 Aug 2016 21:11:20 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH 4.6 57/96] cpufreq: Avoid false-positive WARN_ON()s in cpufreq_update_policy()

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

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

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

commit 742c87bf27d3b715820da6f8a81d6357adbf18f8 upstream.

CPU notifications from the firmware coming in when cpufreq is
suspended cause cpufreq_update_current_freq() to return 0 which
triggers the WARN_ON() in cpufreq_update_policy() for no reason.

Avoid that by checking cpufreq_suspended before calling
cpufreq_update_current_freq().

Fixes: c9d9c929e674 (cpufreq: Abort cpufreq_update_current_freq() for cpufreq_suspended set)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2169,6 +2169,10 @@ int cpufreq_update_policy(unsigned int c
 	 * -> ask driver for current freq and notify governors about a change
 	 */
 	if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
+		if (cpufreq_suspended) {
+			ret = -EAGAIN;
+			goto unlock;
+		}
 		new_policy.cur = cpufreq_update_current_freq(policy);
 		if (WARN_ON(!new_policy.cur)) {
 			ret = -EIO;