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    SubjectRe: [PATCH] cpufreq: schedutil: Avoid using invalid next_freq
    On 09-05-18, 11:44, Rafael J. Wysocki wrote:
    > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    >
    > 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>
    > ---
    > kernel/sched/cpufreq_schedutil.c | 3 ++-
    > 1 file changed, 2 insertions(+), 1 deletion(-)
    >
    > Index: linux-pm/kernel/sched/cpufreq_schedutil.c
    > ===================================================================
    > --- linux-pm.orig/kernel/sched/cpufreq_schedutil.c
    > +++ linux-pm/kernel/sched/cpufreq_schedutil.c
    > @@ -305,7 +305,8 @@ 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 */

    Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

    --
    viresh

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