Commit 8747f202 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Rafael J. Wysocki
Browse files

cpuidle: Allow cpuidle drivers to take over RCU-idle 



Some drivers have to do significant work, some of which relies on RCU
still being active. Instead of using RCU_NONIDLE in the drivers and
flipping RCU back on, allow drivers to take over RCU-idle duty.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Tested-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent a889a23a

drivers/cpuidle/cpuidle.c

+10 −5
Original line number Diff line number Diff line
@@ -138,6 +138,7 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv, 
				struct cpuidle_device *dev, int index)

{

	ktime_t time_start, time_end;

	struct cpuidle_state *target_state = &drv->states[index];



	time_start = ns_to_ktime(local_clock());
@@ -153,8 +154,9 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv, 
	 * suspended is generally unsafe.

	 */

	stop_critical_timings();

	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))

		rcu_idle_enter();

	drv->states[index].enter_s2idle(dev, drv, index);

	target_state->enter_s2idle(dev, drv, index);

	if (WARN_ON_ONCE(!irqs_disabled()))

		local_irq_disable();

	/*
@@ -162,6 +164,7 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv, 
	 * first CPU executing it calls functions containing RCU read-side

	 * critical sections, so tell RCU about that.

	 */

	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))

		rcu_idle_exit();

	tick_unfreeze();

	start_critical_timings();
@@ -239,8 +242,10 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, 
	time_start = ns_to_ktime(local_clock());



	stop_critical_timings();

	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))

		rcu_idle_enter();

	entered_state = target_state->enter(dev, drv, index);

	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))

		rcu_idle_exit();

	start_critical_timings();

include/linux/cpuidle.h

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ struct cpuidle_state { 
#define CPUIDLE_FLAG_UNUSABLE		BIT(3) /* avoid using this state */

#define CPUIDLE_FLAG_OFF		BIT(4) /* disable this state by default */

#define CPUIDLE_FLAG_TLB_FLUSHED	BIT(5) /* idle-state flushes TLBs */

#define CPUIDLE_FLAG_RCU_IDLE		BIT(6) /* idle-state takes care of RCU */



struct cpuidle_device_kobj;

struct cpuidle_state_kobj;

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