cpufreq: intel_pstate: Add locking around HWP requests

To avoid race conditions from multiple threads, increase the scope
of intel_pstate_limits_lock to include HWP requests also.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -853,11 +853,11 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
 
 	limits->no_turbo = clamp_t(int, input, 0, 1);
 
-	mutex_unlock(&intel_pstate_limits_lock);
-
 	if (hwp_active)
 		intel_pstate_hwp_set_online_cpus();
 
+	mutex_unlock(&intel_pstate_limits_lock);
+
 	return count;
 }
 
@@ -882,10 +882,11 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
 				   limits->max_perf_pct);
 	limits->max_perf = div_ext_fp(limits->max_perf_pct, 100);
 
-	mutex_unlock(&intel_pstate_limits_lock);
-
 	if (hwp_active)
 		intel_pstate_hwp_set_online_cpus();
+
+	mutex_unlock(&intel_pstate_limits_lock);
+
 	return count;
 }
 
@@ -910,10 +911,11 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
 				   limits->min_perf_pct);
 	limits->min_perf = div_ext_fp(limits->min_perf_pct, 100);
 
-	mutex_unlock(&intel_pstate_limits_lock);
-
 	if (hwp_active)
 		intel_pstate_hwp_set_online_cpus();
+
+	mutex_unlock(&intel_pstate_limits_lock);
+
 	return count;
 }
 
@@ -1664,7 +1666,6 @@ static void intel_pstate_clear_update_util_hook(unsigned int cpu)
 
 static void intel_pstate_set_performance_limits(struct perf_limits *limits)
 {
-	mutex_lock(&intel_pstate_limits_lock);
 	limits->no_turbo = 0;
 	limits->turbo_disabled = 0;
 	limits->max_perf_pct = 100;
@@ -1675,15 +1676,12 @@ static void intel_pstate_set_performance_limits(struct perf_limits *limits)
 	limits->max_sysfs_pct = 100;
 	limits->min_policy_pct = 0;
 	limits->min_sysfs_pct = 0;
-	mutex_unlock(&intel_pstate_limits_lock);
 }
 
 static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy,
 					    struct perf_limits *limits)
 {
 
-	mutex_lock(&intel_pstate_limits_lock);
-
 	limits->max_policy_pct = DIV_ROUND_UP(policy->max * 100,
 					      policy->cpuinfo.max_freq);
 	limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0, 100);
@@ -1714,8 +1712,6 @@ static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy,
 	limits->max_perf = round_up(limits->max_perf, EXT_FRAC_BITS);
 	limits->min_perf = round_up(limits->min_perf, EXT_FRAC_BITS);
 
-	mutex_unlock(&intel_pstate_limits_lock);
-
 	pr_debug("cpu:%d max_perf_pct:%d min_perf_pct:%d\n", policy->cpu,
 		 limits->max_perf_pct, limits->min_perf_pct);
 }
@@ -1744,6 +1740,8 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
 	if (per_cpu_limits)
 		perf_limits = cpu->perf_limits;
 
+	mutex_lock(&intel_pstate_limits_lock);
+
 	if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
 		if (!perf_limits) {
 			limits = &performance_limits;
@@ -1778,6 +1776,8 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
 
 	intel_pstate_hwp_set_policy(policy);
 
+	mutex_unlock(&intel_pstate_limits_lock);
+
 	return 0;
 }