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    Subject[PATCH 5.12 118/700] thermal/cpufreq_cooling: Update offline CPUs per-cpu thermal_pressure
    Date
    From: Lukasz Luba <lukasz.luba@arm.com>

    [ Upstream commit 2ad8ccc17d1e4270cf65a3f2a07a7534aa23e3fb ]

    The thermal pressure signal gives information to the scheduler about
    reduced CPU capacity due to thermal. It is based on a value stored in
    a per-cpu 'thermal_pressure' variable. The online CPUs will get the
    new value there, while the offline won't. Unfortunately, when the CPU
    is back online, the value read from per-cpu variable might be wrong
    (stale data). This might affect the scheduler decisions, since it
    sees the CPU capacity differently than what is actually available.

    Fix it by making sure that all online+offline CPUs would get the
    proper value in their per-cpu variable when thermal framework sets
    capping.

    Fixes: f12e4f66ab6a3 ("thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping")
    Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
    Link: https://lore.kernel.org/r/20210614191030.22241-1-lukasz.luba@arm.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/thermal/cpufreq_cooling.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
    index 6956581ed7a4..b8ded3aef371 100644
    --- a/drivers/thermal/cpufreq_cooling.c
    +++ b/drivers/thermal/cpufreq_cooling.c
    @@ -487,7 +487,7 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
    ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
    if (ret >= 0) {
    cpufreq_cdev->cpufreq_state = state;
    - cpus = cpufreq_cdev->policy->cpus;
    + cpus = cpufreq_cdev->policy->related_cpus;
    max_capacity = arch_scale_cpu_capacity(cpumask_first(cpus));
    capacity = frequency * max_capacity;
    capacity /= cpufreq_cdev->policy->cpuinfo.max_freq;
    --
    2.30.2


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