Merge tag 'pm-6.12-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management fix from Rafael Wysocki:
 "Fix a locking issue in the asymmetric CPU capacity setup code in the
  intel_pstate driver that may lead to a deadlock if CPU online/offline
  runs in parallel with the code in question, which is unlikely but not
  impossible (Rafael Wysocki)"

* tag 'pm-6.12-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: intel_pstate: Rearrange locking in hybrid_init_cpu_capacity_scaling()

1 files changed, 16 insertions, 19 deletions

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index cd2ac1ba53d2..400337f3b572 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1028,26 +1028,29 @@ static void hybrid_update_cpu_capacity_scaling(void)
 	}
 }
 
-static void __hybrid_init_cpu_capacity_scaling(void)
+static void __hybrid_refresh_cpu_capacity_scaling(void)
 {
 	hybrid_max_perf_cpu = NULL;
 	hybrid_update_cpu_capacity_scaling();
 }
 
-static void hybrid_init_cpu_capacity_scaling(bool refresh)
+static void hybrid_refresh_cpu_capacity_scaling(void)
 {
-	bool disable_itmt = false;
+	guard(mutex)(&hybrid_capacity_lock);
 
-	mutex_lock(&hybrid_capacity_lock);
+	__hybrid_refresh_cpu_capacity_scaling();
+}
 
+static void hybrid_init_cpu_capacity_scaling(bool refresh)
+{
 	/*
 	 * If hybrid_max_perf_cpu is set at this point, the hybrid CPU capacity
 	 * scaling has been enabled already and the driver is just changing the
 	 * operation mode.
 	 */
 	if (refresh) {
-		__hybrid_init_cpu_capacity_scaling();
-		goto unlock;
+		hybrid_refresh_cpu_capacity_scaling();
+		return;
 	}
 
 	/*
@@ -1056,19 +1059,13 @@ static void hybrid_init_cpu_capacity_scaling(bool refresh)
 	 * do not do that when SMT is in use.
 	 */
 	if (hwp_is_hybrid && !sched_smt_active() && arch_enable_hybrid_capacity_scale()) {
-		__hybrid_init_cpu_capacity_scaling();
-		disable_itmt = true;
-	}
-
-unlock:
-	mutex_unlock(&hybrid_capacity_lock);
-
-	/*
-	 * Disabling ITMT causes sched domains to be rebuilt to disable asym
-	 * packing and enable asym capacity.
-	 */
-	if (disable_itmt)
+		hybrid_refresh_cpu_capacity_scaling();
+		/*
+		 * Disabling ITMT causes sched domains to be rebuilt to disable asym
+		 * packing and enable asym capacity.
+		 */
 		sched_clear_itmt_support();
+	}
 }
 
 static bool hybrid_clear_max_perf_cpu(void)
@@ -1404,7 +1401,7 @@ static void intel_pstate_update_limits_for_all(void)
 	mutex_lock(&hybrid_capacity_lock);
 
 	if (hybrid_max_perf_cpu)
-		__hybrid_init_cpu_capacity_scaling();
+		__hybrid_refresh_cpu_capacity_scaling();
 
 	mutex_unlock(&hybrid_capacity_lock);
 }