Commit 99e9acc2 authored May 09, 2018 by Rafael J. Wysocki Committed by Greg Kroah-Hartman May 16, 2018

cpufreq: schedutil: Avoid using invalid next_freq



commit 97739501f207efe33145b918817f305b822987f8 upstream.

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 b7eaf1aa (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: b7eaf1aa (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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 64a03d3b

kernel/sched/cpufreq_schedutil.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -282,7 +282,8 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
		* 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 */