Messages in this thread Patch in this message | | | From | Bo Yan <> | Subject | [PATCH] cpufreq: skip cpufreq resume if it's not suspended | Date | Tue, 23 Jan 2018 13:57:55 -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 cpufreq_suspended first, if it's false, that means cpufreq_suspend was not called in the first place, so do not resume cpufreq.
Signed-off-by: Bo Yan <byan@nvidia.com> --- 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) -- 2.7.4
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