Commit 76934e49 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpuidle: Add sanity check for exit latency and target residency 



Make __cpuidle_driver_init() fail if the exit latency of one of the
driver's idle states is less than its target residency which would
break cpuidle assumptions.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Reviewed-by: default avatarChristian Loehle <christian.loehle@arm.com>
[ rjw: Changelog fix ]
Link: https://patch.msgid.link/12779486.O9o76ZdvQC@rafael.j.wysocki


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 07d81570

drivers/cpuidle/driver.c

+14 −2
Original line number Diff line number Diff line
@@ -152,7 +152,7 @@ static void cpuidle_setup_broadcast_timer(void *arg) 
 * __cpuidle_driver_init - initialize the driver's internal data

 * @drv: a valid pointer to a struct cpuidle_driver

 */

static void __cpuidle_driver_init(struct cpuidle_driver *drv)

static int __cpuidle_driver_init(struct cpuidle_driver *drv)

{

	int i;
@@ -193,7 +193,17 @@ static void __cpuidle_driver_init(struct cpuidle_driver *drv) 
			s->exit_latency_ns =  0;

		else

			s->exit_latency = div_u64(s->exit_latency_ns, NSEC_PER_USEC);



		/*

		 * Ensure that the exit latency of a CPU idle state does not

		 * exceed its target residency which is assumed in cpuidle in

		 * multiple places.

		 */

		if (s->exit_latency_ns > s->target_residency_ns)

			return -EINVAL;

	}



	return 0;

}



/**
@@ -223,7 +233,9 @@ static int __cpuidle_register_driver(struct cpuidle_driver *drv) 
	if (cpuidle_disabled())

		return -ENODEV;



	__cpuidle_driver_init(drv);

	ret = __cpuidle_driver_init(drv);

	if (ret)

		return ret;



	ret = __cpuidle_set_driver(drv);

	if (ret)