From 01e04f466e12e883907937eb04a9010533363f55 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Fri, 27 Feb 2015 00:39:21 +0100 Subject: 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 Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel) --- kernel/sched/idle.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel') 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; } -- cgit v1.3-14-g43fede From dfcacc154fb38fdb2c243c3dbbdc1f26a64cedc8 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 2 Mar 2015 22:25:37 +0100 Subject: cpuidle: Clean up fallback handling in cpuidle_idle_call() Move the fallback code path in cpuidle_idle_call() to the end of the function to avoid jumping to a label in an if () branch. Signed-off-by: Rafael J. Wysocki --- kernel/sched/idle.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index f59198bda1bf..84b93b68482a 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -124,20 +124,8 @@ static void cpuidle_idle_call(void) * Fall back to the default arch idle method on errors. */ next_state = cpuidle_select(drv, dev); - if (next_state < 0) { -use_default: - /* - * We can't use the cpuidle framework, let's use the default - * idle routine. - */ - if (current_clr_polling_and_test()) - local_irq_enable(); - else - arch_cpu_idle(); - - goto exit_idle; - } - + if (next_state < 0) + goto use_default; /* * The idle task must be scheduled, it is pointless to @@ -195,6 +183,19 @@ exit_idle: rcu_idle_exit(); start_critical_timings(); + return; + +use_default: + /* + * We can't use the cpuidle framework, let's use the default + * idle routine. + */ + if (current_clr_polling_and_test()) + local_irq_enable(); + else + arch_cpu_idle(); + + goto exit_idle; } /* -- cgit v1.3-14-g43fede From 17f480342026e54000731acaa69bf32787ce46cb Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Fri, 27 Feb 2015 00:07:55 +0100 Subject: genirq / PM: Add flag for shared NO_SUSPEND interrupt lines It currently is required that all users of NO_SUSPEND interrupt lines pass the IRQF_NO_SUSPEND flag when requesting the IRQ or the WARN_ON_ONCE() in irq_pm_install_action() will trigger. That is done to warn about situations in which unprepared interrupt handlers may be run unnecessarily for suspended devices and may attempt to access those devices by mistake. However, it may cause drivers that have no technical reasons for using IRQF_NO_SUSPEND to set that flag just because they happen to share the interrupt line with something like a timer. Moreover, the generic handling of wakeup interrupts introduced by commit 9ce7a25849e8 (genirq: Simplify wakeup mechanism) only works for IRQs without any NO_SUSPEND users, so the drivers of wakeup devices needing to use shared NO_SUSPEND interrupt lines for signaling system wakeup generally have to detect wakeup in their interrupt handlers. Thus if they happen to share an interrupt line with a NO_SUSPEND user, they also need to request that their interrupt handlers be run after suspend_device_irqs(). In both cases the reason for using IRQF_NO_SUSPEND is not because the driver in question has a genuine need to run its interrupt handler after suspend_device_irqs(), but because it happens to share the line with some other NO_SUSPEND user. Otherwise, the driver would do without IRQF_NO_SUSPEND just fine. To make it possible to specify that condition explicitly, introduce a new IRQ action handler flag for shared IRQs, IRQF_COND_SUSPEND, that, when set, will indicate to the IRQ core that the interrupt user is generally fine with suspending the IRQ, but it also can tolerate handler invocations after suspend_device_irqs() and, in particular, it is capable of detecting system wakeup and triggering it as appropriate from its interrupt handler. That will allow us to work around a problem with a shared timer interrupt line on at91 platforms. Link: http://marc.info/?l=linux-kernel&m=142252777602084&w=2 Link: http://marc.info/?t=142252775300011&r=1&w=2 Link: https://lkml.org/lkml/2014/12/15/552 Reported-by: Boris Brezillon Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel) Acked-by: Mark Rutland --- include/linux/interrupt.h | 5 +++++ include/linux/irqdesc.h | 1 + kernel/irq/manage.c | 7 ++++++- kernel/irq/pm.c | 7 ++++++- 4 files changed, 18 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 606771c7cac2..2e88580194f0 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -59,6 +59,10 @@ * IRQF_NO_THREAD - Interrupt cannot be threaded * IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device * resume time. + * IRQF_COND_SUSPEND - If the IRQ is shared with a NO_SUSPEND user, execute this + * interrupt handler after suspending interrupts. For system + * wakeup devices users need to implement wakeup detection in + * their interrupt handlers. */ #define IRQF_DISABLED 0x00000020 #define IRQF_SHARED 0x00000080 @@ -72,6 +76,7 @@ #define IRQF_FORCE_RESUME 0x00008000 #define IRQF_NO_THREAD 0x00010000 #define IRQF_EARLY_RESUME 0x00020000 +#define IRQF_COND_SUSPEND 0x00040000 #define IRQF_TIMER (__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD) diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index faf433af425e..dd1109fb241e 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -78,6 +78,7 @@ struct irq_desc { #ifdef CONFIG_PM_SLEEP unsigned int nr_actions; unsigned int no_suspend_depth; + unsigned int cond_suspend_depth; unsigned int force_resume_depth; #endif #ifdef CONFIG_PROC_FS diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 196a06fbc122..886d09e691d5 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1474,8 +1474,13 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler, * otherwise we'll have trouble later trying to figure out * which interrupt is which (messes up the interrupt freeing * logic etc). + * + * Also IRQF_COND_SUSPEND only makes sense for shared interrupts and + * it cannot be set along with IRQF_NO_SUSPEND. */ - if ((irqflags & IRQF_SHARED) && !dev_id) + if (((irqflags & IRQF_SHARED) && !dev_id) || + (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) || + ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND))) return -EINVAL; desc = irq_to_desc(irq); diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c index 3ca532592704..5204a6d1b985 100644 --- a/kernel/irq/pm.c +++ b/kernel/irq/pm.c @@ -43,9 +43,12 @@ void irq_pm_install_action(struct irq_desc *desc, struct irqaction *action) if (action->flags & IRQF_NO_SUSPEND) desc->no_suspend_depth++; + else if (action->flags & IRQF_COND_SUSPEND) + desc->cond_suspend_depth++; WARN_ON_ONCE(desc->no_suspend_depth && - desc->no_suspend_depth != desc->nr_actions); + (desc->no_suspend_depth + + desc->cond_suspend_depth) != desc->nr_actions); } /* @@ -61,6 +64,8 @@ void irq_pm_remove_action(struct irq_desc *desc, struct irqaction *action) if (action->flags & IRQF_NO_SUSPEND) desc->no_suspend_depth--; + else if (action->flags & IRQF_COND_SUSPEND) + desc->cond_suspend_depth--; } static bool suspend_device_irq(struct irq_desc *desc, int irq) -- cgit v1.3-14-g43fede From ef2b22ac540c018bd574d1846ab95b9bfcf38702 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 2 Mar 2015 22:26:55 +0100 Subject: cpuidle / sleep: Use broadcast timer for states that stop local timer Commit 381063133246 (PM / sleep: Re-implement suspend-to-idle handling) overlooked the fact that entering some sufficiently deep idle states by CPUs may cause their local timers to stop and in those cases it is necessary to switch over to a broadcast timer prior to entering the idle state. If the cpuidle driver in use does not provide the new ->enter_freeze callback for any of the idle states, that problem affects suspend-to-idle too, but it is not taken into account after the changes made by commit 381063133246. Fix that by changing the definition of cpuidle_enter_freeze() and re-arranging of the code in cpuidle_idle_call(), so the former does not call cpuidle_enter() any more and the fallback case is handled by cpuidle_idle_call() directly. Fixes: 381063133246 (PM / sleep: Re-implement suspend-to-idle handling) Reported-and-tested-by: Lorenzo Pieralisi Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel) --- drivers/cpuidle/cpuidle.c | 62 +++++++++++++++++------------------------------ include/linux/cpuidle.h | 17 +++++++++++-- kernel/sched/idle.c | 30 ++++++++++++++++------- 3 files changed, 58 insertions(+), 51 deletions(-) (limited to 'kernel') diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 8b3e132b6a01..080bd2dbde4b 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -44,8 +44,8 @@ void disable_cpuidle(void) off = 1; } -static bool cpuidle_not_available(struct cpuidle_driver *drv, - struct cpuidle_device *dev) +bool cpuidle_not_available(struct cpuidle_driver *drv, + struct cpuidle_device *dev) { return off || !initialized || !drv || !dev || !dev->enabled; } @@ -72,14 +72,8 @@ int cpuidle_play_dead(void) return -ENODEV; } -/** - * cpuidle_find_deepest_state - Find deepest state meeting specific conditions. - * @drv: cpuidle driver for the given CPU. - * @dev: cpuidle device for the given CPU. - * @freeze: Whether or not the state should be suitable for suspend-to-idle. - */ -static int cpuidle_find_deepest_state(struct cpuidle_driver *drv, - struct cpuidle_device *dev, bool freeze) +static int find_deepest_state(struct cpuidle_driver *drv, + struct cpuidle_device *dev, bool freeze) { unsigned int latency_req = 0; int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1; @@ -98,6 +92,17 @@ static int cpuidle_find_deepest_state(struct cpuidle_driver *drv, return ret; } +/** + * cpuidle_find_deepest_state - Find the deepest available idle state. + * @drv: cpuidle driver for the given CPU. + * @dev: cpuidle device for the given CPU. + */ +int cpuidle_find_deepest_state(struct cpuidle_driver *drv, + struct cpuidle_device *dev) +{ + return find_deepest_state(drv, dev, false); +} + static void enter_freeze_proper(struct cpuidle_driver *drv, struct cpuidle_device *dev, int index) { @@ -119,46 +124,26 @@ static void enter_freeze_proper(struct cpuidle_driver *drv, /** * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle. + * @drv: cpuidle driver for the given CPU. + * @dev: cpuidle device for the given CPU. * * 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. + * them and enter it with frozen tick. */ -void cpuidle_enter_freeze(void) +int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev) { - struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); - struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); int index; - if (cpuidle_not_available(drv, dev)) - goto fallback; - /* * Find the deepest state with ->enter_freeze present, which guarantees * that interrupts won't be enabled when it exits and allows the tick to * be frozen safely. */ - index = cpuidle_find_deepest_state(drv, dev, true); - if (index >= 0) { + index = find_deepest_state(drv, dev, true); + if (index >= 0) enter_freeze_proper(drv, dev, index); - local_irq_enable(); - return; - } - /* - * It is not safe to freeze the tick, find the deepest state available - * at all and try to enter it normally. - */ - index = cpuidle_find_deepest_state(drv, dev, false); - if (index >= 0) { - cpuidle_enter(drv, dev, index); - return; - } - - fallback: - arch_cpu_idle(); + return index; } /** @@ -217,9 +202,6 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, */ int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) { - if (cpuidle_not_available(drv, dev)) - return -ENODEV; - return cpuidle_curr_governor->select(drv, dev); } diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index f551a9299ac9..306178d7309f 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -126,6 +126,8 @@ struct cpuidle_driver { #ifdef CONFIG_CPU_IDLE extern void disable_cpuidle(void); +extern bool cpuidle_not_available(struct cpuidle_driver *drv, + struct cpuidle_device *dev); extern int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev); @@ -150,11 +152,17 @@ extern void cpuidle_resume(void); extern int cpuidle_enable_device(struct cpuidle_device *dev); extern void cpuidle_disable_device(struct cpuidle_device *dev); extern int cpuidle_play_dead(void); -extern void cpuidle_enter_freeze(void); +extern int cpuidle_find_deepest_state(struct cpuidle_driver *drv, + struct cpuidle_device *dev); +extern int cpuidle_enter_freeze(struct cpuidle_driver *drv, + struct cpuidle_device *dev); extern struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev); #else static inline void disable_cpuidle(void) { } +static inline bool cpuidle_not_available(struct cpuidle_driver *drv, + struct cpuidle_device *dev) +{return true; } static inline int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) {return -ENODEV; } @@ -183,7 +191,12 @@ static inline int cpuidle_enable_device(struct cpuidle_device *dev) {return -ENODEV; } static inline void cpuidle_disable_device(struct cpuidle_device *dev) { } static inline int cpuidle_play_dead(void) {return -ENODEV; } -static inline void cpuidle_enter_freeze(void) { } +static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv, + struct cpuidle_device *dev) +{return -ENODEV; } +static inline int cpuidle_enter_freeze(struct cpuidle_driver *drv, + struct cpuidle_device *dev) +{return -ENODEV; } static inline struct cpuidle_driver *cpuidle_get_cpu_driver( struct cpuidle_device *dev) {return NULL; } #endif diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 84b93b68482a..80014a178342 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -82,6 +82,7 @@ static void cpuidle_idle_call(void) struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); int next_state, entered_state; unsigned int broadcast; + bool reflect; /* * Check if the idle task must be rescheduled. If it is the @@ -105,6 +106,9 @@ static void cpuidle_idle_call(void) */ rcu_idle_enter(); + if (cpuidle_not_available(drv, dev)) + goto use_default; + /* * Suspend-to-idle ("freeze") is a system state in which all user space * has been frozen, all I/O devices have been suspended and the only @@ -115,15 +119,22 @@ static void cpuidle_idle_call(void) * until a proper wakeup interrupt happens. */ if (idle_should_freeze()) { - cpuidle_enter_freeze(); - goto exit_idle; - } + entered_state = cpuidle_enter_freeze(drv, dev); + if (entered_state >= 0) { + local_irq_enable(); + goto exit_idle; + } - /* - * Ask the cpuidle framework to choose a convenient idle state. - * Fall back to the default arch idle method on errors. - */ - next_state = cpuidle_select(drv, dev); + reflect = false; + next_state = cpuidle_find_deepest_state(drv, dev); + } else { + reflect = true; + /* + * Ask the cpuidle framework to choose a convenient idle state. + */ + next_state = cpuidle_select(drv, dev); + } + /* Fall back to the default arch idle method on errors. */ if (next_state < 0) goto use_default; @@ -170,7 +181,8 @@ static void cpuidle_idle_call(void) /* * Give the governor an opportunity to reflect on the outcome */ - cpuidle_reflect(dev, entered_state); + if (reflect) + cpuidle_reflect(dev, entered_state); exit_idle: __current_set_polling(); -- cgit v1.3-14-g43fede