Messages in this thread | | | Subject | Re: [PATCH] cpufreq: reinitialize new policy min/max when writing scaling_(max|min)_freq | From | "Wangtao (Kevin, Kirin)" <> | Date | Sat, 26 May 2018 14:50:46 +0800 |
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在 2018/5/24 15:45, Rafael J. Wysocki 写道: > On Thu, May 24, 2018 at 8:43 AM, Kevin Wangtao > <kevin.wangtao@hisilicon.com> wrote: >> consider such situation, current user_policy.min is 1000000, >> current user_policy.max is 1200000, in cpufreq_set_policy, >> other driver may update policy.min to 1200000, policy.max to >> 1300000. After that, If we input "echo 1300000 > scaling_min_freq", >> then user_policy.min will be 1300000, and user_policy.max is >> still 1200000, because the input value is checked with policy.max >> not user_policy.max. if we get all related cpus offline and >> online again, it will cause cpufreq_init_policy fail because >> user_policy.min is higher than user_policy.max. > > How do you reproduce this, exactly? I can also reproduce this issue with upstream code, write max frequency to scaling_max_freq and scaling_min_freq, run benchmark to let cpu cooling take effect to clip freq, then write the cliped freq to scaling_max_freq, thus user_policy.min is still max frequency but user_policy.max is cliped freq which is lower than max frequency. > >> The solution is when user space tries to write scaling_(max|min)_freq, >> the min/max of new_policy should be reinitialized with min/max >> of user_policy, like what cpufreq_update_policy does. >> >> Signed-off-by: Kevin Wangtao <kevin.wangtao@hisilicon.com> >> --- >> drivers/cpufreq/cpufreq.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >> index b79c532..8b33e08 100644 >> --- a/drivers/cpufreq/cpufreq.c >> +++ b/drivers/cpufreq/cpufreq.c >> @@ -697,6 +697,8 @@ static ssize_t store_##file_name \ >> struct cpufreq_policy new_policy; \ >> \ >> memcpy(&new_policy, policy, sizeof(*policy)); \ >> + new_policy->min = policy->user_policy.min; \ >> + new_policy->max = policy->user_policy.max; \ > > It looks like you haven't even tried to build this, have you? > >> \ >> ret = sscanf(buf, "%u", &new_policy.object); \ >> if (ret != 1) \ >> -- >> 2.8.1 >> > > . >
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