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cpufreq: schedutil: Avoid using invalid next_freq

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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 <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>
This commit is contained in:
Rafael J. Wysocki 2018-05-09 11:44:56 +02:00
parent a744490f12
commit 97739501f2
1 changed files with 2 additions and 1 deletions
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3
kernel/sched/cpufreq_schedutil.c
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@ -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 * Do not reduce the frequency if the CPU has not been idle
* recently, as the reduction is likely to be premature then. * 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; next_f = sg_policy->next_freq;
/* Reset cached freq as next_freq has changed */ /* Reset cached freq as next_freq has changed */