diff options
Diffstat (limited to 'include/linux/hrtimer.h')
| -rw-r--r-- | include/linux/hrtimer.h | 167 |
1 files changed, 90 insertions, 77 deletions
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 05f6df1fd..76dd4f0da 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -53,34 +53,25 @@ enum hrtimer_restart { * * 0x00 inactive * 0x01 enqueued into rbtree - * 0x02 callback function running - * 0x04 timer is migrated to another cpu * - * Special cases: - * 0x03 callback function running and enqueued - * (was requeued on another CPU) - * 0x05 timer was migrated on CPU hotunplug + * The callback state is not part of the timer->state because clearing it would + * mean touching the timer after the callback, this makes it impossible to free + * the timer from the callback function. * - * The "callback function running and enqueued" status is only possible on - * SMP. It happens for example when a posix timer expired and the callback + * Therefore we track the callback state in: + * + * timer->base->cpu_base->running == timer + * + * On SMP it is possible to have a "callback function running and enqueued" + * status. It happens for example when a posix timer expired and the callback * queued a signal. Between dropping the lock which protects the posix timer * and reacquiring the base lock of the hrtimer, another CPU can deliver the - * signal and rearm the timer. We have to preserve the callback running state, - * as otherwise the timer could be removed before the softirq code finishes the - * the handling of the timer. - * - * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state - * to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This - * also affects HRTIMER_STATE_MIGRATE where the preservation is not - * necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is - * enqueued on the new cpu. + * signal and rearm the timer. * * All state transitions are protected by cpu_base->lock. */ #define HRTIMER_STATE_INACTIVE 0x00 #define HRTIMER_STATE_ENQUEUED 0x01 -#define HRTIMER_STATE_CALLBACK 0x02 -#define HRTIMER_STATE_MIGRATE 0x04 /** * struct hrtimer - the basic hrtimer structure @@ -130,6 +121,12 @@ struct hrtimer_sleeper { struct task_struct *task; }; +#ifdef CONFIG_64BIT +# define HRTIMER_CLOCK_BASE_ALIGN 64 +#else +# define HRTIMER_CLOCK_BASE_ALIGN 32 +#endif + /** * struct hrtimer_clock_base - the timer base for a specific clock * @cpu_base: per cpu clock base @@ -137,9 +134,7 @@ struct hrtimer_sleeper { * timer to a base on another cpu. * @clockid: clock id for per_cpu support * @active: red black tree root node for the active timers - * @resolution: the resolution of the clock, in nanoseconds * @get_time: function to retrieve the current time of the clock - * @softirq_time: the time when running the hrtimer queue in the softirq * @offset: offset of this clock to the monotonic base */ struct hrtimer_clock_base { @@ -147,11 +142,9 @@ struct hrtimer_clock_base { int index; clockid_t clockid; struct timerqueue_head active; - ktime_t resolution; ktime_t (*get_time)(void); - ktime_t softirq_time; ktime_t offset; -}; +} __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN))); enum hrtimer_base_type { HRTIMER_BASE_MONOTONIC, @@ -165,11 +158,16 @@ enum hrtimer_base_type { * struct hrtimer_cpu_base - the per cpu clock bases * @lock: lock protecting the base and associated clock bases * and timers + * @seq: seqcount around __run_hrtimer + * @running: pointer to the currently running hrtimer * @cpu: cpu number * @active_bases: Bitfield to mark bases with active timers - * @clock_was_set: Indicates that clock was set from irq context. + * @clock_was_set_seq: Sequence counter of clock was set events + * @migration_enabled: The migration of hrtimers to other cpus is enabled + * @nohz_active: The nohz functionality is enabled * @expires_next: absolute time of the next event which was scheduled * via clock_set_next_event() + * @next_timer: Pointer to the first expiring timer * @in_hrtirq: hrtimer_interrupt() is currently executing * @hres_active: State of high resolution mode * @hang_detected: The last hrtimer interrupt detected a hang @@ -178,27 +176,38 @@ enum hrtimer_base_type { * @nr_hangs: Total number of hrtimer interrupt hangs * @max_hang_time: Maximum time spent in hrtimer_interrupt * @clock_base: array of clock bases for this cpu + * + * Note: next_timer is just an optimization for __remove_hrtimer(). + * Do not dereference the pointer because it is not reliable on + * cross cpu removals. */ struct hrtimer_cpu_base { raw_spinlock_t lock; + seqcount_t seq; + struct hrtimer *running; unsigned int cpu; unsigned int active_bases; - unsigned int clock_was_set; + unsigned int clock_was_set_seq; + bool migration_enabled; + bool nohz_active; #ifdef CONFIG_HIGH_RES_TIMERS + unsigned int in_hrtirq : 1, + hres_active : 1, + hang_detected : 1; ktime_t expires_next; - int in_hrtirq; - int hres_active; - int hang_detected; - unsigned long nr_events; - unsigned long nr_retries; - unsigned long nr_hangs; - ktime_t max_hang_time; + struct hrtimer *next_timer; + unsigned int nr_events; + unsigned int nr_retries; + unsigned int nr_hangs; + unsigned int max_hang_time; #endif struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES]; -}; +} ____cacheline_aligned; static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time) { + BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN); + timer->node.expires = time; timer->_softexpires = time; } @@ -262,19 +271,16 @@ static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer) return ktime_sub(timer->node.expires, timer->base->get_time()); } -#ifdef CONFIG_HIGH_RES_TIMERS -struct clock_event_device; - -extern void hrtimer_interrupt(struct clock_event_device *dev); - -/* - * In high resolution mode the time reference must be read accurate - */ static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) { return timer->base->get_time(); } +#ifdef CONFIG_HIGH_RES_TIMERS +struct clock_event_device; + +extern void hrtimer_interrupt(struct clock_event_device *dev); + static inline int hrtimer_is_hres_active(struct hrtimer *timer) { return timer->base->cpu_base->hres_active; @@ -295,21 +301,16 @@ extern void hrtimer_peek_ahead_timers(void); extern void clock_was_set_delayed(void); +extern unsigned int hrtimer_resolution; + #else # define MONOTONIC_RES_NSEC LOW_RES_NSEC # define KTIME_MONOTONIC_RES KTIME_LOW_RES -static inline void hrtimer_peek_ahead_timers(void) { } +#define hrtimer_resolution (unsigned int)LOW_RES_NSEC -/* - * In non high resolution mode the time reference is taken from - * the base softirq time variable. - */ -static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) -{ - return timer->base->softirq_time; -} +static inline void hrtimer_peek_ahead_timers(void) { } static inline int hrtimer_is_hres_active(struct hrtimer *timer) { @@ -353,49 +354,47 @@ static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { } #endif /* Basic timer operations: */ -extern int hrtimer_start(struct hrtimer *timer, ktime_t tim, - const enum hrtimer_mode mode); -extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, +extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, unsigned long range_ns, const enum hrtimer_mode mode); -extern int -__hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, - unsigned long delta_ns, - const enum hrtimer_mode mode, int wakeup); + +/** + * hrtimer_start - (re)start an hrtimer on the current CPU + * @timer: the timer to be added + * @tim: expiry time + * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or + * relative (HRTIMER_MODE_REL) + */ +static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim, + const enum hrtimer_mode mode) +{ + hrtimer_start_range_ns(timer, tim, 0, mode); +} extern int hrtimer_cancel(struct hrtimer *timer); extern int hrtimer_try_to_cancel(struct hrtimer *timer); -static inline int hrtimer_start_expires(struct hrtimer *timer, - enum hrtimer_mode mode) +static inline void hrtimer_start_expires(struct hrtimer *timer, + enum hrtimer_mode mode) { unsigned long delta; ktime_t soft, hard; soft = hrtimer_get_softexpires(timer); hard = hrtimer_get_expires(timer); delta = ktime_to_ns(ktime_sub(hard, soft)); - return hrtimer_start_range_ns(timer, soft, delta, mode); + hrtimer_start_range_ns(timer, soft, delta, mode); } -static inline int hrtimer_restart(struct hrtimer *timer) +static inline void hrtimer_restart(struct hrtimer *timer) { - return hrtimer_start_expires(timer, HRTIMER_MODE_ABS); + hrtimer_start_expires(timer, HRTIMER_MODE_ABS); } /* Query timers: */ extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer); -extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp); -extern ktime_t hrtimer_get_next_event(void); +extern u64 hrtimer_get_next_event(void); -/* - * A timer is active, when it is enqueued into the rbtree or the - * callback function is running or it's in the state of being migrated - * to another cpu. - */ -static inline int hrtimer_active(const struct hrtimer *timer) -{ - return timer->state != HRTIMER_STATE_INACTIVE; -} +extern bool hrtimer_active(const struct hrtimer *timer); /* * Helper function to check, whether the timer is on one of the queues @@ -411,14 +410,29 @@ static inline int hrtimer_is_queued(struct hrtimer *timer) */ static inline int hrtimer_callback_running(struct hrtimer *timer) { - return timer->state & HRTIMER_STATE_CALLBACK; + return timer->base->cpu_base->running == timer; } /* Forward a hrtimer so it expires after now: */ extern u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval); -/* Forward a hrtimer so it expires after the hrtimer's current now */ +/** + * hrtimer_forward_now - forward the timer expiry so it expires after now + * @timer: hrtimer to forward + * @interval: the interval to forward + * + * Forward the timer expiry so it will expire after the current time + * of the hrtimer clock base. Returns the number of overruns. + * + * Can be safely called from the callback function of @timer. If + * called from other contexts @timer must neither be enqueued nor + * running the callback and the caller needs to take care of + * serialization. + * + * Note: This only updates the timer expiry value and does not requeue + * the timer. + */ static inline u64 hrtimer_forward_now(struct hrtimer *timer, ktime_t interval) { @@ -443,7 +457,6 @@ extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode); /* Soft interrupt function to run the hrtimer queues: */ extern void hrtimer_run_queues(void); -extern void hrtimer_run_pending(void); /* Bootup initialization: */ extern void __init hrtimers_init(void); |