From 97739501f207efe33145b918817f305b822987f8 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Wed, 9 May 2018 11:44:56 +0200
Subject: [PATCH] cpufreq: schedutil: Avoid using invalid next_freq
Patch-mainline: v4.17-rc5
Git-commit: 97739501f207efe33145b918817f305b822987f8
References: git-fixes

If the next_freq field of struct sugov_policy is set to UINT_MAX,
it shouldn't be used for updating the CPU frequency (this is a
special "invalid" value), but after commit b7eaf1aab9f8 (cpufreq:
schedutil: Avoid reducing frequency of busy CPUs prematurely) it
may be passed as the new frequency to sugov_update_commit() in
sugov_update_single().

Fix that by adding an extra check for the special UINT_MAX value
of next_freq to sugov_update_single().

Fixes: b7eaf1aab9f8 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely)
Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.12+ <stable@vger.kernel.org> # 4.12+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Matt Fleming <mfleming@suse.de>
---
 kernel/sched/cpufreq_schedutil.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -236,7 +236,8 @@ static void sugov_update_single(struct u
 		 * Do not reduce the frequency if the CPU has not been idle
 		 * recently, as the reduction is likely to be premature then.
 		 */
-		if (busy && next_f < sg_policy->next_freq) {
+		if (busy && next_f < sg_policy->next_freq &&
+		    sg_policy->next_freq != UINT_MAX) {
 			next_f = sg_policy->next_freq;
 
 			/* Reset cached freq as next_freq has changed */