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| author |   Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-02-27 00:39:21 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-02-28 23:46:24 +0100 |
| commit | 01e04f466e12e883907937eb04a9010533363f55 (patch) | |
| tree | 3c10e3c6c051d508bdf655d5e06162b328ffe7cf | |
| parent | Linux 4.0-rc1 (diff) | |
| download | linux-dev-01e04f466e12e883907937eb04a9010533363f55.tar.xz linux-dev-01e04f466e12e883907937eb04a9010533363f55.zip | |
idle / sleep: Avoid excessive disabling and enabling interrupts
Disabling interrupts at the end of cpuidle_enter_freeze() is not
useful, because its caller, cpuidle_idle_call(), re-enables them
right away after invoking it.
To avoid that unnecessary back and forth dance with interrupts,
make cpuidle_enter_freeze() enable interrupts after calling
enter_freeze_proper() and drop the local_irq_disable() at its
end, so that all of the code paths in it end up with interrupts
enabled. Then, cpuidle_idle_call() will not need to re-enable
interrupts after calling cpuidle_enter_freeze() any more, because
the latter will return with interrupts enabled, in analogy with
cpuidle_enter().
Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 6 | ||||
| -rw-r--r-- | kernel/sched/idle.c | 1 |
2 files changed, 3 insertions, 4 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 4d534582514e..b573f584b15a 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -117,6 +117,8 @@ static void enter_freeze_proper(struct cpuidle_driver *drv, * If there are states with the ->enter_freeze callback, find the deepest of * them and enter it with frozen tick. Otherwise, find the deepest state * available and enter it normally. + * + * Returns with enabled interrupts. */ void cpuidle_enter_freeze(void) { @@ -132,6 +134,7 @@ void cpuidle_enter_freeze(void) index = cpuidle_find_deepest_state(drv, dev, true); if (index >= 0) { enter_freeze_proper(drv, dev, index); + local_irq_enable(); return; } @@ -144,9 +147,6 @@ void cpuidle_enter_freeze(void) cpuidle_enter(drv, dev, index); else arch_cpu_idle(); - - /* Interrupts are enabled again here. */ - local_irq_disable(); } /** diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 94b2d7b88a27..f59198bda1bf 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -116,7 +116,6 @@ static void cpuidle_idle_call(void) */ if (idle_should_freeze()) { cpuidle_enter_freeze(); - local_irq_enable(); goto exit_idle; } |