Commit 0a9b9d17 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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()
parents 4ba05b0e 1a1030d1

drivers/cpufreq/intel_pstate.c

+16 −19
Original line number Diff line number Diff line
@@ -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;

	}



	/*
@@ -1056,20 +1059,14 @@ 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);



		hybrid_refresh_cpu_capacity_scaling();

		/*

		 * Disabling ITMT causes sched domains to be rebuilt to disable asym

		 * packing and enable asym capacity.

		 */

	if (disable_itmt)

		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);

}