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sched / idle: Drop default_idle_call() fallback from call_cpuidle() 

After commit 9c4b2867ed (cpuidle: menu: Fix menu_select() for
CPUIDLE_DRIVER_STATE_START == 0) it is clear that menu_select()
cannot return negative values.  Moreover, ladder_select_state()
will never return a negative value too, so make find_deepest_state()
return non-negative values too and drop the default_idle_call()
fallback from call_cpuidle().

This eliminates one branch from the idle loop and makes the governors
and find_deepest_state() handle the case when all states have been
disabled from sysfs consistently.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
hifive-unleashed-5.1
Rafael J. Wysocki 2016-01-16 00:54:53 +01:00
parent 10475b34f4
commit 51164251f5
2 changed files with 3 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/cpuidle/cpuidle.c
View File

@ -79,9 +79,9 @@ static int find_deepest_state(struct cpuidle_driver *drv,
bool freeze)
{
unsigned int latency_req = 0;
int i, ret = -ENXIO;
int i, ret = 0;
for (i = 0; i < drv->state_count; i++) {
for (i = 1; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];
struct cpuidle_state_usage *su = &dev->states_usage[i];
@ -243,7 +243,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
* @drv: the cpuidle driver
* @dev: the cpuidle device
*
* Returns the index of the idle state.
* Returns the index of the idle state. The return value must not be negative.
*/
int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
{

6
kernel/sched/idle.c
View File

@ -97,12 +97,6 @@ void default_idle_call(void)
static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
int next_state)
{
/* Fall back to the default arch idle method on errors. */
if (next_state < 0) {
default_idle_call();
return next_state;
}
/*
* The idle task must be scheduled, it is pointless to go to idle, just
* update no idle residency and return.