cpufreq: intel_pstate: Drop driver_registered variable

The driver_registered variable in intel_pstate is used for checking
whether or not the driver has been registered, but intel_pstate_driver
can be used for that too (with the rule that the driver is not
registered as long as it is NULL).

That is a bit more straightforward and the code may be simplified
a bit this way, so modify the driver accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -349,7 +349,7 @@ static struct pstate_adjust_policy pid_params __read_mostly = {
 static int hwp_active __read_mostly;
 static bool per_cpu_limits __read_mostly;
 
-static bool driver_registered __read_mostly;
+static struct cpufreq_driver *intel_pstate_driver __read_mostly;
 
 #ifdef CONFIG_ACPI
 static bool acpi_ppc;
@@ -1035,7 +1035,7 @@ static ssize_t show_turbo_pct(struct kobject *kobj,
 
 	mutex_lock(&intel_pstate_driver_lock);
 
-	if (!driver_registered) {
+	if (!intel_pstate_driver) {
 		mutex_unlock(&intel_pstate_driver_lock);
 		return -EAGAIN;
 	}
@@ -1060,7 +1060,7 @@ static ssize_t show_num_pstates(struct kobject *kobj,
 
 	mutex_lock(&intel_pstate_driver_lock);
 
-	if (!driver_registered) {
+	if (!intel_pstate_driver) {
 		mutex_unlock(&intel_pstate_driver_lock);
 		return -EAGAIN;
 	}
@@ -1080,7 +1080,7 @@ static ssize_t show_no_turbo(struct kobject *kobj,
 
 	mutex_lock(&intel_pstate_driver_lock);
 
-	if (!driver_registered) {
+	if (!intel_pstate_driver) {
 		mutex_unlock(&intel_pstate_driver_lock);
 		return -EAGAIN;
 	}
@@ -1108,7 +1108,7 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
 
 	mutex_lock(&intel_pstate_driver_lock);
 
-	if (!driver_registered) {
+	if (!intel_pstate_driver) {
 		mutex_unlock(&intel_pstate_driver_lock);
 		return -EAGAIN;
 	}
@@ -1155,7 +1155,7 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
 
 	mutex_lock(&intel_pstate_driver_lock);
 
-	if (!driver_registered) {
+	if (!intel_pstate_driver) {
 		mutex_unlock(&intel_pstate_driver_lock);
 		return -EAGAIN;
 	}
@@ -1185,7 +1185,7 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
 
 	mutex_lock(&intel_pstate_driver_lock);
 
-	if (!driver_registered) {
+	if (!intel_pstate_driver) {
 		mutex_unlock(&intel_pstate_driver_lock);
 		return -EAGAIN;
 	}
@@ -2255,7 +2255,7 @@ static struct cpufreq_driver intel_cpufreq = {
 	.name		= "intel_cpufreq",
 };
 
-static struct cpufreq_driver *intel_pstate_driver = &intel_pstate;
+static struct cpufreq_driver *default_driver = &intel_pstate;
 
 static void intel_pstate_driver_cleanup(void)
 {
@@ -2272,15 +2272,17 @@ static void intel_pstate_driver_cleanup(void)
 		}
 	}
 	put_online_cpus();
+	intel_pstate_driver = NULL;
 }
 
-static int intel_pstate_register_driver(void)
+static int intel_pstate_register_driver(struct cpufreq_driver *driver)
 {
 	int ret;
 
 	memset(&global, 0, sizeof(global));
 	global.max_perf_pct = 100;
 
+	intel_pstate_driver = driver;
 	ret = cpufreq_register_driver(intel_pstate_driver);
 	if (ret) {
 		intel_pstate_driver_cleanup();
@@ -2289,10 +2291,6 @@ static int intel_pstate_register_driver(void)
 
 	global.min_perf_pct = min_perf_pct_min();
 
-	mutex_lock(&intel_pstate_limits_lock);
-	driver_registered = true;
-	mutex_unlock(&intel_pstate_limits_lock);
-
 	if (intel_pstate_driver == &intel_pstate && !hwp_active &&
 	    pstate_funcs.get_target_pstate != get_target_pstate_use_cpu_load)
 		intel_pstate_debug_expose_params();
@@ -2309,10 +2307,6 @@ static int intel_pstate_unregister_driver(void)
 	    pstate_funcs.get_target_pstate != get_target_pstate_use_cpu_load)
 		intel_pstate_debug_hide_params();
 
-	mutex_lock(&intel_pstate_limits_lock);
-	driver_registered = false;
-	mutex_unlock(&intel_pstate_limits_lock);
-
 	cpufreq_unregister_driver(intel_pstate_driver);
 	intel_pstate_driver_cleanup();
 
@@ -2321,7 +2315,7 @@ static int intel_pstate_unregister_driver(void)
 
 static ssize_t intel_pstate_show_status(char *buf)
 {
-	if (!driver_registered)
+	if (!intel_pstate_driver)
 		return sprintf(buf, "off\n");
 
 	return sprintf(buf, "%s\n", intel_pstate_driver == &intel_pstate ?
@@ -2333,11 +2327,11 @@ static int intel_pstate_update_status(const char *buf, size_t size)
 	int ret;
 
 	if (size == 3 && !strncmp(buf, "off", size))
-		return driver_registered ?
+		return intel_pstate_driver ?
 			intel_pstate_unregister_driver() : -EINVAL;
 
 	if (size == 6 && !strncmp(buf, "active", size)) {
-		if (driver_registered) {
+		if (intel_pstate_driver) {
 			if (intel_pstate_driver == &intel_pstate)
 				return 0;
 
@@ -2346,12 +2340,11 @@ static int intel_pstate_update_status(const char *buf, size_t size)
 				return ret;
 		}
 
-		intel_pstate_driver = &intel_pstate;
-		return intel_pstate_register_driver();
+		return intel_pstate_register_driver(&intel_pstate);
 	}
 
 	if (size == 7 && !strncmp(buf, "passive", size)) {
-		if (driver_registered) {
+		if (intel_pstate_driver) {
 			if (intel_pstate_driver != &intel_pstate)
 				return 0;
 
@@ -2360,8 +2353,7 @@ static int intel_pstate_update_status(const char *buf, size_t size)
 				return ret;
 		}
 
-		intel_pstate_driver = &intel_cpufreq;
-		return intel_pstate_register_driver();
+		return intel_pstate_register_driver(&intel_cpufreq);
 	}
 
 	return -EINVAL;
@@ -2601,7 +2593,7 @@ static int __init intel_pstate_init(void)
 	intel_pstate_sysfs_expose_params();
 
 	mutex_lock(&intel_pstate_driver_lock);
-	rc = intel_pstate_register_driver();
+	rc = intel_pstate_register_driver(default_driver);
 	mutex_unlock(&intel_pstate_driver_lock);
 	if (rc)
 		return rc;
@@ -2622,7 +2614,7 @@ static int __init intel_pstate_setup(char *str)
 		no_load = 1;
 	} else if (!strcmp(str, "passive")) {
 		pr_info("Passive mode enabled\n");
-		intel_pstate_driver = &intel_cpufreq;
+		default_driver = &intel_cpufreq;
 		no_hwp = 1;
 	}
 	if (!strcmp(str, "no_hwp")) {