From: Bo Yan byan@nvidia.com
[ Upstream commit 703cbaa601ff3fb554d1246c336ba727cc083ea0 ]
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;
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 Acked-by: Viresh Kumar viresh.kumar@linaro.org [ rjw: Dropped printing a message ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Lee Jones lee.jones@linaro.org --- drivers/cpufreq/cpufreq.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index d43cd983a7ec..04101a6dc7f5 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1646,6 +1646,9 @@ void cpufreq_resume(void) if (!cpufreq_driver) return;
+ if (unlikely(!cpufreq_suspended)) + return; + cpufreq_suspended = false;
if (!has_target() && !cpufreq_driver->resume)