From: Bo Yan <byan@nvidia.com>
To: <viresh.kumar@linaro.org>, <rjw@rjwysocki.net>, <sgurrappadi@nvidia.com>
Cc: <linux-pm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Bo Yan <byan@nvidia.com>
Subject: [PATCH] cpufreq: skip cpufreq resume if it's not suspended
Date: Tue, 23 Jan 2018 13:57:55 -0800 [thread overview]
Message-ID: <1516744675-21233-1-git-send-email-byan@nvidia.com> (raw)
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
next reply other threads:[~2018-01-23 21:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 21:57 Bo Yan [this message]
2018-01-24 2:02 ` [PATCH] cpufreq: skip cpufreq resume if it's not suspended Rafael J. Wysocki
2018-01-24 20:53 ` Bo Yan
2018-02-02 11:54 ` Rafael J. Wysocki
2018-02-02 19:34 ` Saravana Kannan
2018-02-02 21:28 ` Bo Yan
2018-02-05 4:01 ` Viresh Kumar
2018-02-05 8:50 ` Rafael J. Wysocki
2018-02-05 9:05 ` Viresh Kumar
2018-02-15 21:27 ` Saravana Kannan
2018-02-15 22:06 ` Rafael J. Wysocki
2018-01-25 19:15 ` [PATCH v2] " Bo Yan
2018-02-05 9:19 ` [PATCH] " Rafael J. Wysocki
2018-02-05 9:23 ` Viresh Kumar
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