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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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
[ rjw: Changelog fix ]
Link: https://patch.msgid.link/12779486.O9o76ZdvQC@rafael.j.wysocki
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2025-11-07 20:07:28 +01:00
parent 07d8157012
commit 76934e495c
1 changed files with 14 additions and 2 deletions
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16
drivers/cpuidle/driver.c
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@ -152,7 +152,7 @@ static void cpuidle_setup_broadcast_timer(void *arg)
* __cpuidle_driver_init - initialize the driver's internal data * __cpuidle_driver_init - initialize the driver's internal data
* @drv: a valid pointer to a struct cpuidle_driver * @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; int i;
@ -193,7 +193,17 @@ static void __cpuidle_driver_init(struct cpuidle_driver *drv)
s->exit_latency_ns = 0; s->exit_latency_ns = 0;
else else
s->exit_latency = div_u64(s->exit_latency_ns, NSEC_PER_USEC); 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()) if (cpuidle_disabled())
return -ENODEV; return -ENODEV;
__cpuidle_driver_init(drv); ret = __cpuidle_driver_init(drv);
if (ret)
return ret;
ret = __cpuidle_set_driver(drv); ret = __cpuidle_set_driver(drv);
if (ret) if (ret)