Messages in this thread | | | Subject | Re: [PATCH] cpufreq: skip cpufreq resume if it's not suspended | From | Bo Yan <> | Date | Fri, 2 Feb 2018 13:28:15 -0800 |
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On 02/02/2018 11:34 AM, Saravana Kannan wrote: > On 02/02/2018 03:54 AM, Rafael J. Wysocki wrote: >> On Wednesday, January 24, 2018 9:53:14 PM CET Bo Yan wrote: >>> >>> On 01/23/2018 06:02 PM, Rafael J. Wysocki wrote: >>>> On Tuesday, January 23, 2018 10:57:55 PM CET Bo Yan wrote: >>>>> drivers/cpufreq/cpufreq.c | 4 ++++ >>>>> 1 file changed, 4 insertions(+) >>>>> >>>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >>>>> index 41d148af7748..95b1c4afe14e 100644 >>>>> --- a/drivers/cpufreq/cpufreq.c >>>>> +++ b/drivers/cpufreq/cpufreq.c >>>>> @@ -1680,6 +1680,10 @@ void cpufreq_resume(void) >>>>> if (!cpufreq_driver) >>>>> return; >>>>> >>>>> + if (unlikely(!cpufreq_suspended)) { >>>>> + pr_warn("%s: resume after failing suspend\n", __func__); >>>>> + return; >>>>> + } >>>>> cpufreq_suspended = false; >>>>> >>>>> if (!has_target() && !cpufreq_driver->resume) >>>>> >>>> Good catch, but rather than doing this it would be better to avoid >>>> calling cpufreq_resume() at all if cpufreq_suspend() has not been >>>> called. >>> Yes, I thought about that, but there is no good way to skip over it >>> without introducing another flag. cpufreq_resume is called by >>> dpm_resume, cpufreq_suspend is called by dpm_suspend. In the failure >>> case, dpm_resume is called, but dpm_suspend is not. So on a higher >>> level >>> it's already unbalanced. >>> >>> One possibility is to rely on the pm_transition flag. So something >>> like: >>> >>> >>> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c >>> index dc259d20c967..8469e6fc2b2c 100644 >>> --- a/drivers/base/power/main.c >>> +++ b/drivers/base/power/main.c >>> @@ -842,6 +842,7 @@ static void async_resume(void *data, async_cookie_t >>> cookie) >>> void dpm_resume(pm_message_t state) >>> { >>> struct device *dev; >>> + bool suspended = (pm_transition.event != PM_EVENT_ON); >>> ktime_t starttime = ktime_get(); >>> >>> trace_suspend_resume(TPS("dpm_resume"), state.event, true); >>> @@ -885,7 +886,8 @@ void dpm_resume(pm_message_t state) >>> async_synchronize_full(); >>> dpm_show_time(starttime, state, NULL); >>> >>> - cpufreq_resume(); >>> + if (likely(suspended)) >>> + cpufreq_resume(); >>> trace_suspend_resume(TPS("dpm_resume"), state.event, false); >>> } >> >> I was thinking about something else. >> >> Anyway, I think your original patch is OK too, but without printing the >> message. Just combine the cpufreq_suspended check with the >> cpufreq_driver >> one and the unlikely() thing is not necessary. >> > > I rather have this fixed in the dpm_suspend/resume() code. This is > just masking the first issue that's being caused by unbalanced error > handling. If that means adding flags in dpm_suspend/resume() then > that's what we should do right now and clean it up later if it can be > improved. Making cpufreq more messy doesn't seem like the right answer. > > Thanks, > Saravana > > dpm_suspend and dpm_resume by themselves are not balanced in this particular case. As it's currently structured, dpm_resume can't be omitted even if dpm_suspend is skipped due to earlier failure. I think checking cpufreq_suspended flag is a reasonable compromise. If we can find a way to make dpm_suspend/dpm_resume also balanced, that will be best.
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