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author | Viresh Kumar <viresh.kumar@linaro.org> | 2015-07-10 01:36:27 +0200 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-07-10 01:36:27 +0200 |
commit | 35afd02e30d6368073df604920c4ea7cddadf5d0 (patch) | |
tree | a3ee1383e9cd2d6c1f50650617d155123b718090 | |
parent | Linux 4.2-rc1 (diff) | |
download | linux-35afd02e30d6368073df604920c4ea7cddadf5d0.tar.xz linux-35afd02e30d6368073df604920c4ea7cddadf5d0.zip |
cpufreq: Initialize the governor again while restoring policy
When all CPUs of a policy are hot-unplugged, we EXIT the governor but
don't mark policy->governor as NULL. This was done in order to keep last
used governor's information intact in sysfs, while the CPUs are offline.
But we also need to clear policy->governor when restoring the policy.
Because policy->governor still points to the last governor while policy
is restored, following sequence of event happens:
- cpufreq_init_policy() called while restoring policy
- find_governor() matches last_governor string for present governors and
returns last used governor's pointer, say ondemand. policy->governor
already has the same address, unless the governor was removed in
between.
- cpufreq_set_policy() is called with both old/new policies governor set
as ondemand.
- Because governors matched, we skip governor initialization and return
after calling __cpufreq_governor(CPUFREQ_GOV_LIMITS). Because the
governor wasn't initialized for this policy, it returned -EBUSY.
- cpufreq_init_policy() exits the policy on this error, but doesn't
destroy it properly (should be fixed separately).
- And so we enter a scenario where the policy isn't completely
initialized but used.
Fix this by setting policy->governor to NULL while restoring the policy.
Reported-and-tested-by: Pi-Cheng Chen <pi-cheng.chen@linaro.org>
Reported-and-tested-by: "Jon Medhurst (Tixy)" <tixy@linaro.org>
Reported-and-tested-by: Steven Rostedt <rostedt@goodmis.org>
Fixes: 18bf3a124ef8 (cpufreq: Mark policy->governor = NULL for inactive policies)
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r-- | drivers/cpufreq/cpufreq.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index b612411655f9..2c22e3902e72 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1132,6 +1132,7 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu) down_write(&policy->rwsem); policy->cpu = cpu; + policy->governor = NULL; up_write(&policy->rwsem); } |