cpufreq: Add and use cpufreq policy locking guards

Introduce "read" and "write" locking guards for cpufreq policies and use
them where applicable in the cpufreq core.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/8518682.T7Z3S40VBb@rjwysocki.net

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 31ede4d998d22d3fbfb440fc4ec9e98e0111976d..a3abd9c0440d0c2156482b25e2c01e211ef62d1f 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1009,17 +1009,16 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
 {
        struct cpufreq_policy *policy = to_policy(kobj);
        struct freq_attr *fattr = to_attr(attr);
-       ssize_t ret = -EBUSY;
 
        if (!fattr->show)
                return -EIO;
 
-       down_read(&policy->rwsem);
+       guard(cpufreq_policy_read)(policy);
+
        if (likely(!policy_is_inactive(policy)))
-               ret = fattr->show(policy, buf);
-       up_read(&policy->rwsem);
+               return fattr->show(policy, buf);
 
-       return ret;
+       return -EBUSY;
 }
 
 static ssize_t store(struct kobject *kobj, struct attribute *attr,
@@ -1027,17 +1026,16 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
 {
        struct cpufreq_policy *policy = to_policy(kobj);
        struct freq_attr *fattr = to_attr(attr);
-       ssize_t ret = -EBUSY;
 
        if (!fattr->store)
                return -EIO;
 
-       down_write(&policy->rwsem);
+       guard(cpufreq_policy_write)(policy);
+
        if (likely(!policy_is_inactive(policy)))
-               ret = fattr->store(policy, buf, count);
-       up_write(&policy->rwsem);
+               return fattr->store(policy, buf, count);
 
-       return ret;
+       return -EBUSY;
 }
 
 static void cpufreq_sysfs_release(struct kobject *kobj)
@@ -1195,7 +1193,8 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
        if (cpumask_test_cpu(cpu, policy->cpus))
                return 0;
 
-       down_write(&policy->rwsem);
+       guard(cpufreq_policy_write)(policy);
+
        if (has_target())
                cpufreq_stop_governor(policy);
 
@@ -1206,7 +1205,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
                if (ret)
                        pr_err("%s: Failed to start governor\n", __func__);
        }
-       up_write(&policy->rwsem);
+
        return ret;
 }
 
@@ -1226,9 +1225,10 @@ static void handle_update(struct work_struct *work)
                container_of(work, struct cpufreq_policy, update);
 
        pr_debug("handle_update for cpu %u called\n", policy->cpu);
-       down_write(&policy->rwsem);
+
+       guard(cpufreq_policy_write)(policy);
+
        refresh_frequency_limits(policy);
-       up_write(&policy->rwsem);
 }
 
 static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq,
@@ -1254,11 +1254,11 @@ static void cpufreq_policy_put_kobj(struct cpufreq_policy *policy)
        struct kobject *kobj;
        struct completion *cmp;
 
-       down_write(&policy->rwsem);
-       cpufreq_stats_free_table(policy);
-       kobj = &policy->kobj;
-       cmp = &policy->kobj_unregister;
-       up_write(&policy->rwsem);
+       scoped_guard(cpufreq_policy_write, policy) {
+               cpufreq_stats_free_table(policy);
+               kobj = &policy->kobj;
+               cmp = &policy->kobj_unregister;
+       }
        kobject_put(kobj);
 
        /*
@@ -1409,7 +1409,7 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy,
        unsigned int j;
        int ret;
 
-       down_write(&policy->rwsem);
+       guard(cpufreq_policy_write)(policy);
 
        policy->cpu = cpu;
        policy->governor = NULL;
@@ -1586,10 +1586,7 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy,
                goto out_destroy_policy;
        }
 
-out_unlock:
-       up_write(&policy->rwsem);
-
-       return ret;
+       return 0;
 
 out_destroy_policy:
        for_each_cpu(j, policy->real_cpus)
@@ -1606,7 +1603,7 @@ out_exit_policy:
 out_clear_policy:
        cpumask_clear(policy->cpus);
 
-       goto out_unlock;
+       return ret;
 }
 
 static int cpufreq_online(unsigned int cpu)
@@ -1754,11 +1751,10 @@ static int cpufreq_offline(unsigned int cpu)
                return 0;
        }
 
-       down_write(&policy->rwsem);
+       guard(cpufreq_policy_write)(policy);
 
        __cpufreq_offline(cpu, policy);
 
-       up_write(&policy->rwsem);
        return 0;
 }
 
@@ -1775,33 +1771,29 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
        if (!policy)
                return;
 
-       down_write(&policy->rwsem);
+       scoped_guard(cpufreq_policy_write, policy) {
+               if (cpu_online(cpu))
+                       __cpufreq_offline(cpu, policy);
 
-       if (cpu_online(cpu))
-               __cpufreq_offline(cpu, policy);
+               remove_cpu_dev_symlink(policy, cpu, dev);
 
-       remove_cpu_dev_symlink(policy, cpu, dev);
+               if (!cpumask_empty(policy->real_cpus))
+                       return;
 
-       if (!cpumask_empty(policy->real_cpus)) {
-               up_write(&policy->rwsem);
-               return;
-       }
+               /*
+                * Unregister cpufreq cooling once all the CPUs of the policy
+                * are removed.
+                */
+               if (cpufreq_thermal_control_enabled(cpufreq_driver)) {
+                       cpufreq_cooling_unregister(policy->cdev);
+                       policy->cdev = NULL;
+               }
 
-       /*
-        * Unregister cpufreq cooling once all the CPUs of the policy are
-        * removed.
-        */
-       if (cpufreq_thermal_control_enabled(cpufreq_driver)) {
-               cpufreq_cooling_unregister(policy->cdev);
-               policy->cdev = NULL;
+               /* We did light-weight exit earlier, do full tear down now */
+               if (cpufreq_driver->offline && cpufreq_driver->exit)
+                       cpufreq_driver->exit(policy);
        }
 
-       /* We did light-weight exit earlier, do full tear down now */
-       if (cpufreq_driver->offline && cpufreq_driver->exit)
-               cpufreq_driver->exit(policy);
-
-       up_write(&policy->rwsem);
-
        cpufreq_policy_free(policy);
 }
 
@@ -1954,15 +1946,16 @@ unsigned int cpufreq_get(unsigned int cpu)
        struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
        unsigned int ret_freq = 0;
 
-       if (policy) {
-               down_read(&policy->rwsem);
+       if (!policy)
+               return 0;
+
+       scoped_guard(cpufreq_policy_read, policy) {
                if (cpufreq_driver->get)
                        ret_freq = __cpufreq_get(policy);
-               up_read(&policy->rwsem);
-
-               cpufreq_cpu_put(policy);
        }
 
+       cpufreq_cpu_put(policy);
+
        return ret_freq;
 }
 EXPORT_SYMBOL(cpufreq_get);
@@ -2022,9 +2015,9 @@ void cpufreq_suspend(void)
 
        for_each_active_policy(policy) {
                if (has_target()) {
-                       down_write(&policy->rwsem);
-                       cpufreq_stop_governor(policy);
-                       up_write(&policy->rwsem);
+                       scoped_guard(cpufreq_policy_write, policy) {
+                               cpufreq_stop_governor(policy);
+                       }
                }
 
                if (cpufreq_driver->suspend && cpufreq_driver->suspend(policy))
@@ -2065,9 +2058,9 @@ void cpufreq_resume(void)
                        pr_err("%s: Failed to resume driver: %s\n", __func__,
                                cpufreq_driver->name);
                } else if (has_target()) {
-                       down_write(&policy->rwsem);
-                       ret = cpufreq_start_governor(policy);
-                       up_write(&policy->rwsem);
+                       scoped_guard(cpufreq_policy_write, policy) {
+                               ret = cpufreq_start_governor(policy);
+                       }
 
                        if (ret)
                                pr_err("%s: Failed to start governor for CPU%u's policy\n",
@@ -2434,15 +2427,9 @@ int cpufreq_driver_target(struct cpufreq_policy *policy,
                          unsigned int target_freq,
                          unsigned int relation)
 {
-       int ret;
+       guard(cpufreq_policy_write)(policy);
 
-       down_write(&policy->rwsem);
-
-       ret = __cpufreq_driver_target(policy, target_freq, relation);
-
-       up_write(&policy->rwsem);
-
-       return ret;
+       return __cpufreq_driver_target(policy, target_freq, relation);
 }
 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
 

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 400fee6427a5c0013c2cba601a0699545b9cde09..cb972d2aa8df7596694de8cdc988f8ab0fa51d81 100644 (file)
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -170,6 +170,12 @@ struct cpufreq_policy {
        struct notifier_block nb_max;
 };
 
+DEFINE_GUARD(cpufreq_policy_write, struct cpufreq_policy *,
+            down_write(&_T->rwsem), up_write(&_T->rwsem))
+
+DEFINE_GUARD(cpufreq_policy_read, struct cpufreq_policy *,
+            down_read(&_T->rwsem), up_read(&_T->rwsem))
+
 /*
  * Used for passing new cpufreq policy data to the cpufreq driver's ->verify()
  * callback for sanitization.  That callback is only expected to modify the min