cpufreq/sched: schedutil: Add helper for governor checks

Add a helper for checking if schedutil is the current governor for
a given cpufreq policy and use it in sched_is_eas_possible() to avoid
accessing cpufreq policy internals directly from there.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <[email protected]>
Reviewed-by: Christian Loehle <[email protected]>
Tested-by: Christian Loehle <[email protected]>
Reviewed-by: Dietmar Eggemann <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: rafaeljw

include/linux/cpufreq.h

@@ -650,6 +650,15 @@ module_exit(__governor##_exit)
 struct cpufreq_governor *cpufreq_default_governor(void);
 struct cpufreq_governor *cpufreq_fallback_governor(void);
 
+#ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL
+bool sugov_is_governor(struct cpufreq_policy *policy);
+#else
+static inline bool sugov_is_governor(struct cpufreq_policy *policy)
+{
+	return false;
+}
+#endif
+
 static inline void cpufreq_policy_apply_limits(struct cpufreq_policy *policy)
 {
 	if (policy->max < policy->cur)

kernel/sched/cpufreq_schedutil.c

@@ -630,7 +630,7 @@ static const struct kobj_type sugov_tunables_ktype = {
 
 /********************** cpufreq governor interface *********************/
 
-struct cpufreq_governor schedutil_gov;
+static struct cpufreq_governor schedutil_gov;
 
 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 {
@@ -909,7 +909,7 @@ static void sugov_limits(struct cpufreq_policy *policy)
 	WRITE_ONCE(sg_policy->limits_changed, true);
 }
 
-struct cpufreq_governor schedutil_gov = {
+static struct cpufreq_governor schedutil_gov = {
 	.name			= "schedutil",
 	.owner			= THIS_MODULE,
 	.flags			= CPUFREQ_GOV_DYNAMIC_SWITCHING,
@@ -927,4 +927,9 @@ struct cpufreq_governor *cpufreq_default_governor(void)
 }
 #endif
 
+bool sugov_is_governor(struct cpufreq_policy *policy)
+{
+	return policy->governor == &schedutil_gov;
+}
+
 cpufreq_governor_init(schedutil_gov);

kernel/sched/sched.h

@@ -3509,8 +3509,6 @@ static inline bool sched_energy_enabled(void)
 	return static_branch_unlikely(&sched_energy_present);
 }
 
-extern struct cpufreq_governor schedutil_gov;
-
 #else /* ! (CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL) */
 
 #define perf_domain_span(pd) NULL

kernel/sched/topology.c

@@ -213,7 +213,7 @@ static bool sched_is_eas_possible(const struct cpumask *cpu_mask)
 {
 	bool any_asym_capacity = false;
 	struct cpufreq_policy *policy;
-	struct cpufreq_governor *gov;
+	bool policy_is_ready;
 	int i;
 
 	/* EAS is enabled for asymmetric CPU capacity topologies. */
@@ -258,9 +258,9 @@ static bool sched_is_eas_possible(const struct cpumask *cpu_mask)
 			}
 			return false;
 		}
-		gov = policy->governor;
+		policy_is_ready = sugov_is_governor(policy);
 		cpufreq_cpu_put(policy);
-		if (gov != &schedutil_gov) {
+		if (!policy_is_ready) {
 			if (sched_debug()) {
 				pr_info("rd %*pbl: Checking EAS, schedutil is mandatory\n",
 					cpumask_pr_args(cpu_mask));