| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 103/132] cpufreq: Skip cpufreq resume if its not suspended | Date | Wed, 27 Nov 2019 21:31:34 +0100 |
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From: Bo Yan <byan@nvidia.com>
commit 703cbaa601ff3fb554d1246c336ba727cc083ea0 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/cpufreq/cpufreq.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1627,6 +1627,9 @@ void cpufreq_resume(void) if (!cpufreq_driver) return; + if (unlikely(!cpufreq_suspended)) + return; + cpufreq_suspended = false; if (!has_target())
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