[PATCH] hrtimer: hrtimer core code (c0a31329) · Commits · e / devices / android_kernel_fairphone_FP3

include/linux/hrtimer.h

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		/*
		* include/linux/hrtimer.h
		*
		* hrtimers - High-resolution kernel timers
		*
		* Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
		* Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
		*
		* data type definitions, declarations, prototypes
		*
		* Started by: Thomas Gleixner and Ingo Molnar
		*
		* For licencing details see kernel-base/COPYING
		*/
		#ifndef _LINUX_HRTIMER_H
		#define _LINUX_HRTIMER_H

		#include <linux/rbtree.h>
		#include <linux/ktime.h>
		#include <linux/init.h>
		#include <linux/list.h>
		#include <linux/wait.h>

		/*
		* Mode arguments of xxx_hrtimer functions:
		*/
		enum hrtimer_mode {
		HRTIMER_ABS, /* Time value is absolute */
		HRTIMER_REL, /* Time value is relative to now */
		};

		enum hrtimer_restart {
		HRTIMER_NORESTART,
		HRTIMER_RESTART,
		};

		/*
		* Timer states:
		*/
		enum hrtimer_state {
		HRTIMER_INACTIVE, /* Timer is inactive */
		HRTIMER_EXPIRED, /* Timer is expired */
		HRTIMER_PENDING, /* Timer is pending */
		};

		struct hrtimer_base;

		/**
		* struct hrtimer - the basic hrtimer structure
		*
		* @node: red black tree node for time ordered insertion
		* @list: list head for easier access to the time ordered list,
		* without walking the red black tree.
		* @expires: the absolute expiry time in the hrtimers internal
		* representation. The time is related to the clock on
		* which the timer is based.
		* @state: state of the timer
		* @function: timer expiry callback function
		* @data: argument for the callback function
		* @base: pointer to the timer base (per cpu and per clock)
		*
		* The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
		*/
		struct hrtimer {
		struct rb_node node;
		struct list_head list;
		ktime_t expires;
		enum hrtimer_state state;
		int (function)(void );
		void *data;
		struct hrtimer_base *base;
		};

		/**
		* struct hrtimer_base - the timer base for a specific clock
		*
		* @index: clock type index for per_cpu support when moving a timer
		* to a base on another cpu.
		* @lock: lock protecting the base and associated timers
		* @active: red black tree root node for the active timers
		* @pending: list of pending timers for simple time ordered access
		* @resolution: the resolution of the clock, in nanoseconds
		* @get_time: function to retrieve the current time of the clock
		* @curr_timer: the timer which is executing a callback right now
		*/
		struct hrtimer_base {
		clockid_t index;
		spinlock_t lock;
		struct rb_root active;
		struct list_head pending;
		unsigned long resolution;
		ktime_t (*get_time)(void);
		struct hrtimer *curr_timer;
		};

		/* Exported timer functions: */

		/* Initialize timers: */
		extern void hrtimer_init(struct hrtimer *timer, const clockid_t which_clock);
		extern void hrtimer_rebase(struct hrtimer *timer, const clockid_t which_clock);


		/* Basic timer operations: */
		extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
		const enum hrtimer_mode mode);
		extern int hrtimer_cancel(struct hrtimer *timer);
		extern int hrtimer_try_to_cancel(struct hrtimer *timer);

		#define hrtimer_restart(timer) hrtimer_start((timer), (timer)->expires, HRTIMER_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);

		static inline int hrtimer_active(const struct hrtimer *timer)
		{
		return timer->state == HRTIMER_PENDING;
		}

		/* Forward a hrtimer so it expires after now: */
		extern unsigned long hrtimer_forward(struct hrtimer *timer,
		const ktime_t interval);

		/* Soft interrupt function to run the hrtimer queues: */
		extern void hrtimer_run_queues(void);

		/* Bootup initialization: */
		extern void __init hrtimers_init(void);

		#endif

include/linux/ktime.h

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		@@ -266,4 +266,19 @@ static inline u64 ktime_to_ns(const ktime_t kt)

		#endif

		/*
		* The resolution of the clocks. The resolution value is returned in
		* the clock_getres() system call to give application programmers an
		* idea of the (in)accuracy of timers. Timer values are rounded up to
		* this resolution values.
		*/
		#define KTIME_REALTIME_RES (NSEC_PER_SEC/HZ)
		#define KTIME_MONOTONIC_RES (NSEC_PER_SEC/HZ)

		/* Get the monotonic time in timespec format: */
		extern void ktime_get_ts(struct timespec *ts);

		/* Get the real (wall-) time in timespec format: */
		#define ktime_get_real_ts(ts) getnstimeofday(ts)

		#endif

init/main.c

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		@@ -485,6 +485,7 @@ asmlinkage void __init start_kernel(void)
		init_IRQ();
		pidhash_init();
		init_timers();
		hrtimers_init();
		softirq_init();
		time_init();

kernel/Makefile

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		@@ -7,7 +7,8 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
		sysctl.o capability.o ptrace.o timer.o user.o \
		signal.o sys.o kmod.o workqueue.o pid.o \
		rcupdate.o intermodule.o extable.o params.o posix-timers.o \
		kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o
		kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
		hrtimer.o

		obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o
		obj-$(CONFIG_FUTEX) += futex.o

kernel/hrtimer.c

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		/*
		* linux/kernel/hrtimer.c
		*
		* Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
		* Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
		*
		* High-resolution kernel timers
		*
		* In contrast to the low-resolution timeout API implemented in
		* kernel/timer.c, hrtimers provide finer resolution and accuracy
		* depending on system configuration and capabilities.
		*
		* These timers are currently used for:
		* - itimers
		* - POSIX timers
		* - nanosleep
		* - precise in-kernel timing
		*
		* Started by: Thomas Gleixner and Ingo Molnar
		*
		* Credits:
		* based on kernel/timer.c
		*
		* For licencing details see kernel-base/COPYING
		*/

		#include <linux/cpu.h>
		#include <linux/module.h>
		#include <linux/percpu.h>
		#include <linux/hrtimer.h>
		#include <linux/notifier.h>
		#include <linux/syscalls.h>
		#include <linux/interrupt.h>

		#include <asm/uaccess.h>

		/**
		* ktime_get - get the monotonic time in ktime_t format
		*
		* returns the time in ktime_t format
		*/
		static ktime_t ktime_get(void)
		{
		struct timespec now;

		ktime_get_ts(&now);

		return timespec_to_ktime(now);
		}

		/**
		* ktime_get_real - get the real (wall-) time in ktime_t format
		*
		* returns the time in ktime_t format
		*/
		static ktime_t ktime_get_real(void)
		{
		struct timespec now;

		getnstimeofday(&now);

		return timespec_to_ktime(now);
		}

		EXPORT_SYMBOL_GPL(ktime_get_real);

		/*
		* The timer bases:
		*/

		#define MAX_HRTIMER_BASES 2

		static DEFINE_PER_CPU(struct hrtimer_base, hrtimer_bases[MAX_HRTIMER_BASES]) =
		{
		{
		.index = CLOCK_REALTIME,
		.get_time = &ktime_get_real,
		.resolution = KTIME_REALTIME_RES,
		},
		{
		.index = CLOCK_MONOTONIC,
		.get_time = &ktime_get,
		.resolution = KTIME_MONOTONIC_RES,
		},
		};

		/**
		* ktime_get_ts - get the monotonic clock in timespec format
		*
		* @ts: pointer to timespec variable
		*
		* The function calculates the monotonic clock from the realtime
		* clock and the wall_to_monotonic offset and stores the result
		* in normalized timespec format in the variable pointed to by ts.
		*/
		void ktime_get_ts(struct timespec *ts)
		{
		struct timespec tomono;
		unsigned long seq;

		do {
		seq = read_seqbegin(&xtime_lock);
		getnstimeofday(ts);
		tomono = wall_to_monotonic;

		} while (read_seqretry(&xtime_lock, seq));

		set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
		ts->tv_nsec + tomono.tv_nsec);
		}

		/*
		* Functions and macros which are different for UP/SMP systems are kept in a
		* single place
		*/
		#ifdef CONFIG_SMP

		#define set_curr_timer(b, t) do { (b)->curr_timer = (t); } while (0)

		/*
		* We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
		* means that all timers which are tied to this base via timer->base are
		* locked, and the base itself is locked too.
		*
		* So __run_timers/migrate_timers can safely modify all timers which could
		* be found on the lists/queues.
		*
		* When the timer's base is locked, and the timer removed from list, it is
		* possible to set timer->base = NULL and drop the lock: the timer remains
		* locked.
		*/
		static struct hrtimer_base lock_hrtimer_base(const struct hrtimer timer,
		unsigned long *flags)
		{
		struct hrtimer_base *base;

		for (;;) {
		base = timer->base;
		if (likely(base != NULL)) {
		spin_lock_irqsave(&base->lock, *flags);
		if (likely(base == timer->base))
		return base;
		/* The timer has migrated to another CPU: */
		spin_unlock_irqrestore(&base->lock, *flags);
		}
		cpu_relax();
		}
		}

		/*
		* Switch the timer base to the current CPU when possible.
		*/
		static inline struct hrtimer_base *
		switch_hrtimer_base(struct hrtimer timer, struct hrtimer_base base)
		{
		struct hrtimer_base *new_base;

		new_base = &__get_cpu_var(hrtimer_bases[base->index]);

		if (base != new_base) {
		/*
		* We are trying to schedule the timer on the local CPU.
		* However we can't change timer's base while it is running,
		* so we keep it on the same CPU. No hassle vs. reprogramming
		* the event source in the high resolution case. The softirq
		* code will take care of this when the timer function has
		* completed. There is no conflict as we hold the lock until
		* the timer is enqueued.
		*/
		if (unlikely(base->curr_timer == timer))
		return base;

		/* See the comment in lock_timer_base() */
		timer->base = NULL;
		spin_unlock(&base->lock);
		spin_lock(&new_base->lock);
		timer->base = new_base;
		}
		return new_base;
		}

		#else /* CONFIG_SMP */

		#define set_curr_timer(b, t) do { } while (0)

		static inline struct hrtimer_base *
		lock_hrtimer_base(const struct hrtimer timer, unsigned long flags)
		{
		struct hrtimer_base *base = timer->base;

		spin_lock_irqsave(&base->lock, *flags);

		return base;
		}

		#define switch_hrtimer_base(t, b) (b)

		#endif /* !CONFIG_SMP */

		/*
		* Functions for the union type storage format of ktime_t which are
		* too large for inlining:
		*/
		#if BITS_PER_LONG < 64
		# ifndef CONFIG_KTIME_SCALAR
		/**
		* ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
		*
		* @kt: addend
		* @nsec: the scalar nsec value to add
		*
		* Returns the sum of kt and nsec in ktime_t format
		*/
		ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
		{
		ktime_t tmp;

		if (likely(nsec < NSEC_PER_SEC)) {
		tmp.tv64 = nsec;
		} else {
		unsigned long rem = do_div(nsec, NSEC_PER_SEC);

		tmp = ktime_set((long)nsec, rem);
		}

		return ktime_add(kt, tmp);
		}

		#else /* CONFIG_KTIME_SCALAR */

		# endif /* !CONFIG_KTIME_SCALAR */

		/*
		* Divide a ktime value by a nanosecond value
		*/
		static unsigned long ktime_divns(const ktime_t kt, nsec_t div)
		{
		u64 dclc, inc, dns;
		int sft = 0;

		dclc = dns = ktime_to_ns(kt);
		inc = div;
		/* Make sure the divisor is less than 2^32: */
		while (div >> 32) {
		sft++;
		div >>= 1;
		}
		dclc >>= sft;
		do_div(dclc, (unsigned long) div);

		return (unsigned long) dclc;
		}

		#else /* BITS_PER_LONG < 64 */
		# define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
		#endif /* BITS_PER_LONG >= 64 */

		/*
		* Counterpart to lock_timer_base above:
		*/
		static inline
		void unlock_hrtimer_base(const struct hrtimer timer, unsigned long flags)
		{
		spin_unlock_irqrestore(&timer->base->lock, *flags);
		}

		/**
		* hrtimer_forward - forward the timer expiry
		*
		* @timer: hrtimer to forward
		* @interval: the interval to forward
		*
		* Forward the timer expiry so it will expire in the future.
		* The number of overruns is added to the overrun field.
		*/
		unsigned long
		hrtimer_forward(struct hrtimer *timer, const ktime_t interval)
		{
		unsigned long orun = 1;
		ktime_t delta, now;

		now = timer->base->get_time();

		delta = ktime_sub(now, timer->expires);

		if (delta.tv64 < 0)
		return 0;

		if (unlikely(delta.tv64 >= interval.tv64)) {
		nsec_t incr = ktime_to_ns(interval);

		orun = ktime_divns(delta, incr);
		timer->expires = ktime_add_ns(timer->expires, incr * orun);
		if (timer->expires.tv64 > now.tv64)
		return orun;
		/*
		* This (and the ktime_add() below) is the
		* correction for exact:
		*/
		orun++;
		}
		timer->expires = ktime_add(timer->expires, interval);

		return orun;
		}

		/*
		* enqueue_hrtimer - internal function to (re)start a timer
		*
		* The timer is inserted in expiry order. Insertion into the
		* red black tree is O(log(n)). Must hold the base lock.
		*/
		static void enqueue_hrtimer(struct hrtimer timer, struct hrtimer_base base)
		{
		struct rb_node **link = &base->active.rb_node;
		struct list_head *prev = &base->pending;
		struct rb_node *parent = NULL;
		struct hrtimer *entry;

		/*
		* Find the right place in the rbtree:
		*/
		while (*link) {
		parent = *link;
		entry = rb_entry(parent, struct hrtimer, node);
		/*
		* We dont care about collisions. Nodes with
		* the same expiry time stay together.
		*/
		if (timer->expires.tv64 < entry->expires.tv64)
		link = &(*link)->rb_left;
		else {
		link = &(*link)->rb_right;
		prev = &entry->list;
		}
		}

		/*
		* Insert the timer to the rbtree and to the sorted list:
		*/
		rb_link_node(&timer->node, parent, link);
		rb_insert_color(&timer->node, &base->active);
		list_add(&timer->list, prev);

		timer->state = HRTIMER_PENDING;
		}


		/*
		* __remove_hrtimer - internal function to remove a timer
		*
		* Caller must hold the base lock.
		*/
		static void __remove_hrtimer(struct hrtimer timer, struct hrtimer_base base)
		{
		/*
		* Remove the timer from the sorted list and from the rbtree:
		*/
		list_del(&timer->list);
		rb_erase(&timer->node, &base->active);
		}

		/*
		* remove hrtimer, called with base lock held
		*/
		static inline int
		remove_hrtimer(struct hrtimer timer, struct hrtimer_base base)
		{
		if (hrtimer_active(timer)) {
		__remove_hrtimer(timer, base);
		timer->state = HRTIMER_INACTIVE;
		return 1;
		}
		return 0;
		}

		/**
		* hrtimer_start - (re)start an relative timer on the current CPU
		*
		* @timer: the timer to be added
		* @tim: expiry time
		* @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
		*
		* Returns:
		* 0 on success
		* 1 when the timer was active
		*/
		int
		hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
		{
		struct hrtimer_base base, new_base;
		unsigned long flags;
		int ret;

		base = lock_hrtimer_base(timer, &flags);

		/* Remove an active timer from the queue: */
		ret = remove_hrtimer(timer, base);

		/* Switch the timer base, if necessary: */
		new_base = switch_hrtimer_base(timer, base);

		if (mode == HRTIMER_REL)
		tim = ktime_add(tim, new_base->get_time());
		timer->expires = tim;

		enqueue_hrtimer(timer, new_base);

		unlock_hrtimer_base(timer, &flags);

		return ret;
		}

		/**
		* hrtimer_try_to_cancel - try to deactivate a timer
		*
		* @timer: hrtimer to stop
		*
		* Returns:
		* 0 when the timer was not active
		* 1 when the timer was active
		* -1 when the timer is currently excuting the callback function and
		* can not be stopped
		*/
		int hrtimer_try_to_cancel(struct hrtimer *timer)
		{
		struct hrtimer_base *base;
		unsigned long flags;
		int ret = -1;

		base = lock_hrtimer_base(timer, &flags);

		if (base->curr_timer != timer)
		ret = remove_hrtimer(timer, base);

		unlock_hrtimer_base(timer, &flags);

		return ret;

		}

		/**
		* hrtimer_cancel - cancel a timer and wait for the handler to finish.
		*
		* @timer: the timer to be cancelled
		*
		* Returns:
		* 0 when the timer was not active
		* 1 when the timer was active
		*/
		int hrtimer_cancel(struct hrtimer *timer)
		{
		for (;;) {
		int ret = hrtimer_try_to_cancel(timer);

		if (ret >= 0)
		return ret;
		}
		}

		/**
		* hrtimer_get_remaining - get remaining time for the timer
		*
		* @timer: the timer to read
		*/
		ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
		{
		struct hrtimer_base *base;
		unsigned long flags;
		ktime_t rem;

		base = lock_hrtimer_base(timer, &flags);
		rem = ktime_sub(timer->expires, timer->base->get_time());
		unlock_hrtimer_base(timer, &flags);

		return rem;
		}

		/**
		* hrtimer_rebase - rebase an initialized hrtimer to a different base
		*
		* @timer: the timer to be rebased
		* @clock_id: the clock to be used
		*/
		void hrtimer_rebase(struct hrtimer *timer, const clockid_t clock_id)
		{
		struct hrtimer_base *bases;

		bases = per_cpu(hrtimer_bases, raw_smp_processor_id());
		timer->base = &bases[clock_id];
		}

		/**
		* hrtimer_init - initialize a timer to the given clock
		*
		* @timer: the timer to be initialized
		* @clock_id: the clock to be used
		*/
		void hrtimer_init(struct hrtimer *timer, const clockid_t clock_id)
		{
		memset(timer, 0, sizeof(struct hrtimer));
		hrtimer_rebase(timer, clock_id);
		}

		/**
		* hrtimer_get_res - get the timer resolution for a clock
		*
		* @which_clock: which clock to query
		* @tp: pointer to timespec variable to store the resolution
		*
		* Store the resolution of the clock selected by which_clock in the
		* variable pointed to by tp.
		*/
		int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
		{
		struct hrtimer_base *bases;

		tp->tv_sec = 0;
		bases = per_cpu(hrtimer_bases, raw_smp_processor_id());
		tp->tv_nsec = bases[which_clock].resolution;

		return 0;
		}

		/*
		* Expire the per base hrtimer-queue:
		*/
		static inline void run_hrtimer_queue(struct hrtimer_base *base)
		{
		ktime_t now = base->get_time();

		spin_lock_irq(&base->lock);

		while (!list_empty(&base->pending)) {
		struct hrtimer *timer;
		int (fn)(void );
		int restart;
		void *data;

		timer = list_entry(base->pending.next, struct hrtimer, list);
		if (now.tv64 <= timer->expires.tv64)
		break;

		fn = timer->function;
		data = timer->data;
		set_curr_timer(base, timer);
		__remove_hrtimer(timer, base);
		spin_unlock_irq(&base->lock);

		/*
		* fn == NULL is special case for the simplest timer
		* variant - wake up process and do not restart:
		*/
		if (!fn) {
		wake_up_process(data);
		restart = HRTIMER_NORESTART;
		} else
		restart = fn(data);

		spin_lock_irq(&base->lock);

		if (restart == HRTIMER_RESTART)
		enqueue_hrtimer(timer, base);
		else
		timer->state = HRTIMER_EXPIRED;
		}
		set_curr_timer(base, NULL);
		spin_unlock_irq(&base->lock);
		}

		/*
		* Called from timer softirq every jiffy, expire hrtimers:
		*/
		void hrtimer_run_queues(void)
		{
		struct hrtimer_base *base = __get_cpu_var(hrtimer_bases);
		int i;

		for (i = 0; i < MAX_HRTIMER_BASES; i++)
		run_hrtimer_queue(&base[i]);
		}

		/*
		* Functions related to boot-time initialization:
		*/
		static void __devinit init_hrtimers_cpu(int cpu)
		{
		struct hrtimer_base *base = per_cpu(hrtimer_bases, cpu);
		int i;

		for (i = 0; i < MAX_HRTIMER_BASES; i++) {
		spin_lock_init(&base->lock);
		INIT_LIST_HEAD(&base->pending);
		base++;
		}
		}

		#ifdef CONFIG_HOTPLUG_CPU

		static void migrate_hrtimer_list(struct hrtimer_base *old_base,
		struct hrtimer_base *new_base)
		{
		struct hrtimer *timer;
		struct rb_node *node;

		while ((node = rb_first(&old_base->active))) {
		timer = rb_entry(node, struct hrtimer, node);
		__remove_hrtimer(timer, old_base);
		timer->base = new_base;
		enqueue_hrtimer(timer, new_base);
		}
		}

		static void migrate_hrtimers(int cpu)
		{
		struct hrtimer_base old_base, new_base;
		int i;

		BUG_ON(cpu_online(cpu));
		old_base = per_cpu(hrtimer_bases, cpu);
		new_base = get_cpu_var(hrtimer_bases);

		local_irq_disable();

		for (i = 0; i < MAX_HRTIMER_BASES; i++) {

		spin_lock(&new_base->lock);
		spin_lock(&old_base->lock);

		BUG_ON(old_base->curr_timer);

		migrate_hrtimer_list(old_base, new_base);

		spin_unlock(&old_base->lock);
		spin_unlock(&new_base->lock);
		old_base++;
		new_base++;
		}

		local_irq_enable();
		put_cpu_var(hrtimer_bases);
		}
		#endif /* CONFIG_HOTPLUG_CPU */

		static int __devinit hrtimer_cpu_notify(struct notifier_block *self,
		unsigned long action, void *hcpu)
		{
		long cpu = (long)hcpu;

		switch (action) {

		case CPU_UP_PREPARE:
		init_hrtimers_cpu(cpu);
		break;

		#ifdef CONFIG_HOTPLUG_CPU
		case CPU_DEAD:
		migrate_hrtimers(cpu);
		break;
		#endif

		default:
		break;
		}

		return NOTIFY_OK;
		}

		static struct notifier_block __devinitdata hrtimers_nb = {
		.notifier_call = hrtimer_cpu_notify,
		};

		void __init hrtimers_init(void)
		{
		hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
		(void *)(long)smp_processor_id());
		register_cpu_notifier(&hrtimers_nb);
		}