Messages in this thread Patch in this message | | | From | Bo Yan <> | Subject | [PATCH v2] cpufreq: skip cpufreq resume if it's not suspended | Date | Thu, 25 Jan 2018 11:15:45 -0800 |
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cpufreq_resume can be called even without preceding cpufreq_suspend. This can happen in following scenario:
suspend_devices_and_enter --> dpm_suspend_start --> dpm_prepare --> device_prepare : this function errors out --> dpm_suspend: this is skipped due to dpm_prepare failure this means cpufreq_suspend is skipped over --> goto Recover_platform, due to previous error --> goto Resume_devices --> dpm_resume_end --> dpm_resume --> cpufreq_resume
In case schedutil is used as frequency governor, cpufreq_resume will eventually call sugov_start, which does following:
memset(sg_cpu, 0, sizeof(*sg_cpu)); ....
This effectively erases function pointer for frequency update, causing crash later on. The function pointer would have been set correctly if subsequent cpufreq_add_update_util_hook runs successfully, but that function returns earlier because cpufreq_suspend was not called:
if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu))) return;
Ideally, suspend should succeed, then things will be fine. But even in case of suspend failure, system should not crash.
The fix is to check the pm_transition status in dpm_resume. if pm_transition.event == PMSG_ON, we know for sure dpm_suspend has not been called, so do not call cpufreq_resume.
Signed-off-by: Bo Yan <byan@nvidia.com> --- drivers/base/power/main.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index 08744b572af6..39829d7a9311 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -921,6 +921,7 @@ 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); @@ -964,7 +965,8 @@ void dpm_resume(pm_message_t state) async_synchronize_full(); dpm_show_time(starttime, state, 0, NULL); - cpufreq_resume(); + if (likely(suspended)) + cpufreq_resume(); trace_suspend_resume(TPS("dpm_resume"), state.event, false); } -- 2.7.4
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