From 8747f2022fe8d8029193707ee86ff5c792cbef9b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 15 Sep 2020 12:32:00 +0200 Subject: [PATCH] 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: Peter Zijlstra (Intel) Reviewed-by: Ulf Hansson Tested-by: Borislav Petkov Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/cpuidle.c | 15 ++++++++++----- include/linux/cpuidle.h | 1 + 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 04becd70cc41..6c7e5621cf9a 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -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(); - rcu_idle_enter(); - drv->states[index].enter_s2idle(dev, drv, index); + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) + rcu_idle_enter(); + target_state->enter_s2idle(dev, drv, index); if (WARN_ON_ONCE(!irqs_disabled())) local_irq_disable(); /* @@ -162,7 +164,8 @@ 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. */ - rcu_idle_exit(); + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) + rcu_idle_exit(); tick_unfreeze(); start_critical_timings(); @@ -239,9 +242,11 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, time_start = ns_to_ktime(local_clock()); stop_critical_timings(); - rcu_idle_enter(); + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) + rcu_idle_enter(); entered_state = target_state->enter(dev, drv, index); - rcu_idle_exit(); + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) + rcu_idle_exit(); start_critical_timings(); sched_clock_idle_wakeup_event(); diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 75895e6363b8..6175c77bf25e 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -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; -- 2.20.1