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cpuidle: Use s64 as exit_latency_ns and target_residency_ns data type

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Subsequent changes will cause the exit_latency_ns and target_residency_ns
fields in struct cpuidle_state to be used in computations in which data
type conversions to u64 may turn a negative number close to zero into
a verly large positive number leading to incorrect results.

In preparation for that, change the data type of the fields mentioned
above to s64, but ensure that they will not be negative themselves.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2021-03-29 20:15:19 +02:00
parent 4c81cb7e64
commit 2ab80d46fe
2 changed files with 6 additions and 2 deletions
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4
drivers/cpuidle/driver.c
View File

@ -181,9 +181,13 @@ static void __cpuidle_driver_init(struct cpuidle_driver *drv)
*/
if (s->target_residency > 0)
s->target_residency_ns = s->target_residency * NSEC_PER_USEC;
else if (s->target_residency_ns < 0)
s->target_residency_ns = 0;
if (s->exit_latency > 0)
s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC;
else if (s->exit_latency_ns < 0)
s->exit_latency_ns = 0;
}
}

4
include/linux/cpuidle.h
View File

@ -49,8 +49,8 @@ struct cpuidle_state {
char name[CPUIDLE_NAME_LEN];
char desc[CPUIDLE_DESC_LEN];
u64 exit_latency_ns;
u64 target_residency_ns;
s64 exit_latency_ns;
s64 target_residency_ns;
unsigned int flags;
unsigned int exit_latency; /* in US */
int power_usage; /* in mW */