Messages in this thread Patch in this message | | | Date | Thu, 4 Feb 2016 12:13:04 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH V2 7/7] cpufreq: Remove cpufreq_governor_lock |
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On 03-02-16, 19:32, Viresh Kumar wrote: > We used to drop policy->rwsem just before calling __cpufreq_governor() > in some cases earlier and so it was possible that __cpufreq_governor() > runs concurrently via separate threads. > > In order to guarantee valid state transitions for governors, > 'governor_enabled' was required to be protected using some locking and > we created cpufreq_governor_lock for that. > > But now, __cpufreq_governor() is always called from within policy->rwsem > held and so 'governor_enabled' is protected against races even without > cpufreq_governor_lock. > > Get rid of the extra lock now. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq.c | 7 ------- > 1 file changed, 7 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 4fc3889ca7c9..7bc8a5ed97e5 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -102,7 +102,6 @@ static LIST_HEAD(cpufreq_governor_list); > static struct cpufreq_driver *cpufreq_driver; > static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data); > static DEFINE_RWLOCK(cpufreq_driver_lock); > -DEFINE_MUTEX(cpufreq_governor_lock); > > /* Flag to suspend/resume CPUFreq governors */ > static bool cpufreq_suspended; > @@ -1963,11 +1962,9 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, > > pr_debug("%s: for CPU %u, event %u\n", __func__, policy->cpu, event); > > - mutex_lock(&cpufreq_governor_lock); > if ((policy->governor_enabled && event == CPUFREQ_GOV_START) > || (!policy->governor_enabled > && (event == CPUFREQ_GOV_LIMITS || event == CPUFREQ_GOV_STOP))) { > - mutex_unlock(&cpufreq_governor_lock); > return -EBUSY; > } > > @@ -1976,8 +1973,6 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, > else if (event == CPUFREQ_GOV_START) > policy->governor_enabled = true; > > - mutex_unlock(&cpufreq_governor_lock); > - > ret = policy->governor->governor(policy, event); > > if (!ret) { > @@ -1987,12 +1982,10 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, > policy->governor->initialized--; > } else { > /* Restore original values */ > - mutex_lock(&cpufreq_governor_lock); > if (event == CPUFREQ_GOV_STOP) > policy->governor_enabled = true; > else if (event == CPUFREQ_GOV_START) > policy->governor_enabled = false; > - mutex_unlock(&cpufreq_governor_lock); > } > > if (((event == CPUFREQ_GOV_POLICY_INIT) && ret) ||
+ minor cleanup:
diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h index ed328a39c4ac..7bed63e14e7d 100644 --- a/drivers/cpufreq/cpufreq_governor.h +++ b/drivers/cpufreq/cpufreq_governor.h @@ -214,7 +214,6 @@ static inline int delay_for_sampling_rate(unsigned int sampling_rate) return delay; } -extern struct mutex cpufreq_governor_lock; extern const struct sysfs_ops governor_sysfs_ops; void gov_add_timers(struct cpufreq_policy *policy, unsigned int delay); -- viresh
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