idle / sleep: Avoid excessive disabling and enabling interrupts (01e04f46) · Commits · 戴 / test

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>

drivers/cpuidle/cpuidle.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -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();
		}

		/**

kernel/sched/idle.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -116,7 +116,6 @@ static void cpuidle_idle_call(void)
		*/
		if (idle_should_freeze()) {
		cpuidle_enter_freeze();
		local_irq_enable();
		goto exit_idle;
		}

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