cpufreq: schedutil: Avoid using invalid next_freq

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 b7eaf1aab9 (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: b7eaf1aab9 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely)
Reported-by: Viresh Kumar <[email protected]>
Cc: 4.12+ <[email protected]> # 4.12+
Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
This commit is contained in:
Rafael J. Wysocki 2018-05-09 11:44:56 +02:00
commit 97739501f2

View file

@ -305,7 +305,8 @@ 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 */