mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 19:00:25 +00:00
cpufreq: governor: Quit work-handlers early if governor is stopped
gov_queue_work() acquires cpufreq_governor_lock to allow cpufreq_governor_stop() to drain delayed work items possibly scheduled on CPUs that share the policy with a CPU being taken offline. However, the same goal may be achieved in a more straightforward way if the policy pointer in the struct cpu_dbs_info matching the policy CPU is reset upfront by cpufreq_governor_stop() under the timer_mutex belonging to it and checked against NULL, under the same lock, at the beginning of dbs_timer(). In that case every instance of dbs_timer() run for a struct cpu_dbs_info sharing the policy pointer in question after cpufreq_governor_stop() has started will notice that that pointer is NULL and bail out immediately without queuing up any new work items. In turn, gov_cancel_work() called by cpufreq_governor_stop() before destroying timer_mutex will wait for all of the delayed work items currently running on the CPUs sharing the policy to drop the mutex, so it may be destroyed safely. Make cpufreq_governor_stop() and dbs_timer() work as described and modify gov_queue_work() so it does not acquire cpufreq_governor_lock any more. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
parent
539342f60b
commit
3a91b069ea
1 changed files with 23 additions and 10 deletions
|
@ -171,10 +171,6 @@ void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
|
|||
{
|
||||
int i;
|
||||
|
||||
mutex_lock(&cpufreq_governor_lock);
|
||||
if (!policy->governor_enabled)
|
||||
goto out_unlock;
|
||||
|
||||
if (!all_cpus) {
|
||||
/*
|
||||
* Use raw_smp_processor_id() to avoid preemptible warnings.
|
||||
|
@ -188,9 +184,6 @@ void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
|
|||
for_each_cpu(i, policy->cpus)
|
||||
__gov_queue_work(i, dbs_data, delay);
|
||||
}
|
||||
|
||||
out_unlock:
|
||||
mutex_unlock(&cpufreq_governor_lock);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(gov_queue_work);
|
||||
|
||||
|
@ -229,13 +222,24 @@ static void dbs_timer(struct work_struct *work)
|
|||
struct cpu_dbs_info *cdbs = container_of(work, struct cpu_dbs_info,
|
||||
dwork.work);
|
||||
struct cpu_common_dbs_info *shared = cdbs->shared;
|
||||
struct cpufreq_policy *policy = shared->policy;
|
||||
struct dbs_data *dbs_data = policy->governor_data;
|
||||
struct cpufreq_policy *policy;
|
||||
struct dbs_data *dbs_data;
|
||||
unsigned int sampling_rate, delay;
|
||||
bool modify_all = true;
|
||||
|
||||
mutex_lock(&shared->timer_mutex);
|
||||
|
||||
policy = shared->policy;
|
||||
|
||||
/*
|
||||
* Governor might already be disabled and there is no point continuing
|
||||
* with the work-handler.
|
||||
*/
|
||||
if (!policy)
|
||||
goto unlock;
|
||||
|
||||
dbs_data = policy->governor_data;
|
||||
|
||||
if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
|
||||
struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
|
||||
|
||||
|
@ -252,6 +256,7 @@ static void dbs_timer(struct work_struct *work)
|
|||
delay = dbs_data->cdata->gov_dbs_timer(cdbs, dbs_data, modify_all);
|
||||
gov_queue_work(dbs_data, policy, delay, modify_all);
|
||||
|
||||
unlock:
|
||||
mutex_unlock(&shared->timer_mutex);
|
||||
}
|
||||
|
||||
|
@ -478,9 +483,17 @@ static int cpufreq_governor_stop(struct cpufreq_policy *policy,
|
|||
if (!shared || !shared->policy)
|
||||
return -EBUSY;
|
||||
|
||||
/*
|
||||
* Work-handler must see this updated, as it should not proceed any
|
||||
* further after governor is disabled. And so timer_mutex is taken while
|
||||
* updating this value.
|
||||
*/
|
||||
mutex_lock(&shared->timer_mutex);
|
||||
shared->policy = NULL;
|
||||
mutex_unlock(&shared->timer_mutex);
|
||||
|
||||
gov_cancel_work(dbs_data, policy);
|
||||
|
||||
shared->policy = NULL;
|
||||
mutex_destroy(&shared->timer_mutex);
|
||||
return 0;
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue