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authorViresh Kumar <viresh.kumar@linaro.org>2013-08-31 16:18:23 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-09-10 04:49:46 +0400
commit19c763031acb831a5ab9c1a701b7fedda073eb3f (patch)
tree86ddfcb2266d1cc4946d7b24f2a6320277517cc2 /include/linux/cpufreq.h
parentf73d39338444d9915c746403bd98b145ff9d2ba4 (diff)
downloadlinux-19c763031acb831a5ab9c1a701b7fedda073eb3f.tar.xz
cpufreq: serialize calls to __cpufreq_governor()
We can't take a big lock around __cpufreq_governor() as this causes recursive locking for some cases. But calls to this routine must be serialized for every policy. Otherwise we can see some unpredictable events. For example, consider following scenario: __cpufreq_remove_dev() __cpufreq_governor(policy, CPUFREQ_GOV_STOP); policy->governor->governor(policy, CPUFREQ_GOV_STOP); cpufreq_governor_dbs() case CPUFREQ_GOV_STOP: mutex_destroy(&cpu_cdbs->timer_mutex) cpu_cdbs->cur_policy = NULL; <PREEMPT> store() __cpufreq_set_policy() __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); policy->governor->governor(policy, CPUFREQ_GOV_LIMITS); case CPUFREQ_GOV_LIMITS: mutex_lock(&cpu_cdbs->timer_mutex); <-- Warning (destroyed mutex) if (policy->max < cpu_cdbs->cur_policy->cur) <- cur_policy == NULL And so store() will eventually result in a crash if cur_policy is NULL at this point. Introduce an additional variable which would guarantee serialization here. Reported-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'include/linux/cpufreq.h')
-rw-r--r--include/linux/cpufreq.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index d568f3975eeb..cca885dac1d3 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -76,6 +76,7 @@ struct cpufreq_policy {
struct cpufreq_governor *governor; /* see below */
void *governor_data;
bool governor_enabled; /* governor start/stop flag */
+ bool governor_busy;
struct work_struct update; /* if update_policy() needs to be
* called, but you're in IRQ context */