diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/Makefile | 5 | ||||
| -rw-r--r-- | kernel/time/clockevents.c | 8 | ||||
| -rw-r--r-- | kernel/time/tick-broadcast-hrtimer.c | 106 | ||||
| -rw-r--r-- | kernel/time/tick-broadcast.c | 60 | ||||
| -rw-r--r-- | kernel/time/tick-internal.h | 6 |
5 files changed, 173 insertions, 12 deletions
diff --git a/kernel/time/Makefile b/kernel/time/Makefile index 9250130..57a413f 100644 --- a/kernel/time/Makefile +++ b/kernel/time/Makefile @@ -3,7 +3,10 @@ obj-y += timeconv.o posix-clock.o alarmtimer.o obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD) += clockevents.o obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o -obj-$(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) += tick-broadcast.o +ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y) + obj-y += tick-broadcast.o + obj-$(CONFIG_TICK_ONESHOT) += tick-broadcast-hrtimer.o +endif obj-$(CONFIG_GENERIC_SCHED_CLOCK) += sched_clock.o obj-$(CONFIG_TICK_ONESHOT) += tick-oneshot.o obj-$(CONFIG_TICK_ONESHOT) += tick-sched.o diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index c2eb27b..f50f783 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -526,12 +526,13 @@ void clockevents_resume(void) #ifdef CONFIG_GENERIC_CLOCKEVENTS /** * clockevents_notify - notification about relevant events + * Returns 0 on success, any other value on error */ -void clockevents_notify(unsigned long reason, void *arg) +int clockevents_notify(unsigned long reason, void *arg) { struct clock_event_device *dev, *tmp; unsigned long flags; - int cpu; + int cpu, ret = 0; raw_spin_lock_irqsave(&clockevents_lock, flags); @@ -544,7 +545,7 @@ void clockevents_notify(unsigned long reason, void *arg) case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: case CLOCK_EVT_NOTIFY_BROADCAST_EXIT: - tick_broadcast_oneshot_control(reason); + ret = tick_broadcast_oneshot_control(reason); break; case CLOCK_EVT_NOTIFY_CPU_DYING: @@ -587,6 +588,7 @@ void clockevents_notify(unsigned long reason, void *arg) break; } raw_spin_unlock_irqrestore(&clockevents_lock, flags); + return ret; } EXPORT_SYMBOL_GPL(clockevents_notify); diff --git a/kernel/time/tick-broadcast-hrtimer.c b/kernel/time/tick-broadcast-hrtimer.c new file mode 100644 index 0000000..eb682d5 --- /dev/null +++ b/kernel/time/tick-broadcast-hrtimer.c @@ -0,0 +1,106 @@ +/* + * linux/kernel/time/tick-broadcast-hrtimer.c + * This file emulates a local clock event device + * via a pseudo clock device. + */ +#include <linux/cpu.h> +#include <linux/err.h> +#include <linux/hrtimer.h> +#include <linux/interrupt.h> +#include <linux/percpu.h> +#include <linux/profile.h> +#include <linux/clockchips.h> +#include <linux/sched.h> +#include <linux/smp.h> +#include <linux/module.h> + +#include "tick-internal.h" + +static struct hrtimer bctimer; + +static void bc_set_mode(enum clock_event_mode mode, + struct clock_event_device *bc) +{ + switch (mode) { + case CLOCK_EVT_MODE_SHUTDOWN: + /* + * Note, we cannot cancel the timer here as we might + * run into the following live lock scenario: + * + * cpu 0 cpu1 + * lock(broadcast_lock); + * hrtimer_interrupt() + * bc_handler() + * tick_handle_oneshot_broadcast(); + * lock(broadcast_lock); + * hrtimer_cancel() + * wait_for_callback() + */ + hrtimer_try_to_cancel(&bctimer); + break; + default: + break; + } +} + +/* + * This is called from the guts of the broadcast code when the cpu + * which is about to enter idle has the earliest broadcast timer event. + */ +static int bc_set_next(ktime_t expires, struct clock_event_device *bc) +{ + /* + * We try to cancel the timer first. If the callback is on + * flight on some other cpu then we let it handle it. If we + * were able to cancel the timer nothing can rearm it as we + * own broadcast_lock. + * + * However we can also be called from the event handler of + * ce_broadcast_hrtimer itself when it expires. We cannot + * restart the timer because we are in the callback, but we + * can set the expiry time and let the callback return + * HRTIMER_RESTART. + */ + if (hrtimer_try_to_cancel(&bctimer) >= 0) { + hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED); + /* Bind the "device" to the cpu */ + bc->bound_on = smp_processor_id(); + } else if (bc->bound_on == smp_processor_id()) { + hrtimer_set_expires(&bctimer, expires); + } + return 0; +} + +static struct clock_event_device ce_broadcast_hrtimer = { + .set_mode = bc_set_mode, + .set_next_ktime = bc_set_next, + .features = CLOCK_EVT_FEAT_ONESHOT | + CLOCK_EVT_FEAT_KTIME | + CLOCK_EVT_FEAT_HRTIMER, + .rating = 0, + .bound_on = -1, + .min_delta_ns = 1, + .max_delta_ns = KTIME_MAX, + .min_delta_ticks = 1, + .max_delta_ticks = ULONG_MAX, + .mult = 1, + .shift = 0, + .cpumask = cpu_all_mask, +}; + +static enum hrtimer_restart bc_handler(struct hrtimer *t) +{ + ce_broadcast_hrtimer.event_handler(&ce_broadcast_hrtimer); + + if (ce_broadcast_hrtimer.next_event.tv64 == KTIME_MAX) + return HRTIMER_NORESTART; + + return HRTIMER_RESTART; +} + +void tick_setup_hrtimer_broadcast(void) +{ + hrtimer_init(&bctimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); + bctimer.function = bc_handler; + clockevents_register_device(&ce_broadcast_hrtimer); +} diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 8a95408b..2256515 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -629,24 +629,61 @@ again: raw_spin_unlock(&tick_broadcast_lock); } +static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu) +{ + if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER)) + return 0; + if (bc->next_event.tv64 == KTIME_MAX) + return 0; + return bc->bound_on == cpu ? -EBUSY : 0; +} + +static void broadcast_shutdown_local(struct clock_event_device *bc, + struct clock_event_device *dev) +{ + /* + * For hrtimer based broadcasting we cannot shutdown the cpu + * local device if our own event is the first one to expire or + * if we own the broadcast timer. + */ + if (bc->features & CLOCK_EVT_FEAT_HRTIMER) { + if (broadcast_needs_cpu(bc, smp_processor_id())) + return; + if (dev->next_event.tv64 < bc->next_event.tv64) + return; + } + clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); +} + +static void broadcast_move_bc(int deadcpu) +{ + struct clock_event_device *bc = tick_broadcast_device.evtdev; + + if (!bc || !broadcast_needs_cpu(bc, deadcpu)) + return; + /* This moves the broadcast assignment to this cpu */ + clockevents_program_event(bc, bc->next_event, 1); +} + /* * Powerstate information: The system enters/leaves a state, where * affected devices might stop + * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups. */ -void tick_broadcast_oneshot_control(unsigned long reason) +int tick_broadcast_oneshot_control(unsigned long reason) { struct clock_event_device *bc, *dev; struct tick_device *td; unsigned long flags; ktime_t now; - int cpu; + int cpu, ret = 0; /* * Periodic mode does not care about the enter/exit of power * states */ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) - return; + return 0; /* * We are called with preemtion disabled from the depth of the @@ -657,7 +694,7 @@ void tick_broadcast_oneshot_control(unsigned long reason) dev = td->evtdev; if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) - return; + return 0; bc = tick_broadcast_device.evtdev; @@ -665,7 +702,7 @@ void tick_broadcast_oneshot_control(unsigned long reason) if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) { if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) { WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask)); - clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); + broadcast_shutdown_local(bc, dev); /* * We only reprogram the broadcast timer if we * did not mark ourself in the force mask and @@ -678,6 +715,16 @@ void tick_broadcast_oneshot_control(unsigned long reason) dev->next_event.tv64 < bc->next_event.tv64) tick_broadcast_set_event(bc, cpu, dev->next_event, 1); } + /* + * If the current CPU owns the hrtimer broadcast + * mechanism, it cannot go deep idle and we remove the + * CPU from the broadcast mask. We don't have to go + * through the EXIT path as the local timer is not + * shutdown. + */ + ret = broadcast_needs_cpu(bc, cpu); + if (ret) + cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask); } else { if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) { clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); @@ -745,6 +792,7 @@ void tick_broadcast_oneshot_control(unsigned long reason) } out: raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); + return ret; } /* @@ -851,6 +899,8 @@ void tick_shutdown_broadcast_oneshot(unsigned int *cpup) cpumask_clear_cpu(cpu, tick_broadcast_pending_mask); cpumask_clear_cpu(cpu, tick_broadcast_force_mask); + broadcast_move_bc(cpu); + raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); } diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h index 7e5e7f8..ea5242b 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -47,7 +47,7 @@ extern int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *)); extern void tick_resume_oneshot(void); # ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST extern void tick_broadcast_setup_oneshot(struct clock_event_device *bc); -extern void tick_broadcast_oneshot_control(unsigned long reason); +extern int tick_broadcast_oneshot_control(unsigned long reason); extern void tick_broadcast_switch_to_oneshot(void); extern void tick_shutdown_broadcast_oneshot(unsigned int *cpup); extern int tick_resume_broadcast_oneshot(struct clock_event_device *bc); @@ -59,7 +59,7 @@ static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); } -static inline void tick_broadcast_oneshot_control(unsigned long reason) { } +static inline int tick_broadcast_oneshot_control(unsigned long reason) { return 0; } static inline void tick_broadcast_switch_to_oneshot(void) { } static inline void tick_shutdown_broadcast_oneshot(unsigned int *cpup) { } static inline int tick_broadcast_oneshot_active(void) { return 0; } @@ -88,7 +88,7 @@ static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); } -static inline void tick_broadcast_oneshot_control(unsigned long reason) { } +static inline int tick_broadcast_oneshot_control(unsigned long reason) { return 0; } static inline void tick_shutdown_broadcast_oneshot(unsigned int *cpup) { } static inline int tick_resume_broadcast_oneshot(struct clock_event_device *bc) { |