- 根目录:
- kernel
- time
- hrtimer.c
/*
* linux/kernel/hrtimer.c
*
* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
* Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
*
* 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
*
* Help, testing, suggestions, bugfixes, improvements were
* provided by:
*
* George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
* et. al.
*
* For licencing details see kernel-base/COPYING
*/
#include <linux/cpu.h>
#include <linux/export.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
#include <linux/notifier.h>
#include <linux/syscalls.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/tick.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <linux/debugobjects.h>
#include <linux/sched.h>
#include <linux/sched/sysctl.h>
#include <linux/sched/rt.h>
#include <linux/sched/deadline.h>
#include <linux/timer.h>
#include <linux/freezer.h>
#include <asm/uaccess.h>
#include <trace/events/timer.h>
#include "tick-internal.h"
/*
* The timer bases:
*
* There are more clockids than hrtimer bases. Thus, we index
* into the timer bases by the hrtimer_base_type enum. When trying
* to reach a base using a clockid, hrtimer_clockid_to_base()
* is used to convert from clockid to the proper hrtimer_base_type.
*/
DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
{
.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
.seq = SEQCNT_ZERO(hrtimer_bases.seq),
.clock_base =
{
{
.index = HRTIMER_BASE_MONOTONIC,
.clockid = CLOCK_MONOTONIC,
.get_time = &ktime_get,
},
{
.index = HRTIMER_BASE_REALTIME,
.clockid = CLOCK_REALTIME,
.get_time = &ktime_get_real,
},
{
.index = HRTIMER_BASE_BOOTTIME,
.clockid = CLOCK_BOOTTIME,
.get_time = &ktime_get_boottime,
},
{
.index = HRTIMER_BASE_TAI,
.clockid = CLOCK_TAI,
.get_time = &ktime_get_clocktai,
},
}
};
static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
[CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
[CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
[CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
[CLOCK_TAI] = HRTIMER_BASE_TAI,
};
static inline int hrtimer_clockid_to_base(clockid_t clock_id)
{
return hrtimer_clock_to_base_table[clock_id];
}
/*
* Functions and macros which are different for UP/SMP systems are kept in a
* single place
*/
#ifdef CONFIG_SMP
/*
* We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
* such that hrtimer_callback_running() can unconditionally dereference
* timer->base->cpu_base
*/
static struct hrtimer_cpu_base migration_cpu_base = {
.seq = SEQCNT_ZERO(migration_cpu_base),
.clock_base = { { .cpu_base = &migration_cpu_base, }, },
};
#define migration_base migration_cpu_base.clock_base[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 = &migration_base and drop the lock: the timer
* remains locked.
*/
static
struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
unsigned long *flags)
{
struct hrtimer_clock_base *base;
for (;;) {
base = timer->base;
if (likely(base != &migration_base)) {
raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
if (likely(base == timer->base))
return base;
/* The timer has migrated to another CPU: */
raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
}
cpu_relax();
}
}
/*
* With HIGHRES=y we do not migrate the timer when it is expiring
* before the next event on the target cpu because we cannot reprogram
* the target cpu hardware and we would cause it to fire late.
*
* Called with cpu_base->lock of target cpu held.
*/
static int
hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
{
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires;
if (!new_base->cpu_base->hres_active)
return 0;
expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
return expires.tv64 <= new_base->cpu_base->expires_next.tv64;
#else
return 0;
#endif
}
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
static inline
struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
int pinned)
{
if (pinned || !base->migration_enabled)
return base;
return &per_cpu(hrtimer_bases, get_nohz_timer_target());
}
#else
static inline
struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
int pinned)
{
return base;
}
#endif
/*
* We switch the timer base to a power-optimized selected CPU target,
* if:
* - NO_HZ_COMMON is enabled
* - timer migration is enabled
* - the timer callback is not running
* - the timer is not the first expiring timer on the new target
*
* If one of the above requirements is not fulfilled we move the timer
* to the current CPU or leave it on the previously assigned CPU if
* the timer callback is currently running.
*/
static inline struct hrtimer_clock_base *
switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
int pinned)
{
struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
struct hrtimer_clock_base *new_base;
int basenum = base->index;
this_cpu_base = this_cpu_ptr(&hrtimer_bases);
new_cpu_base = get_target_base(this_cpu_base, pinned);
again:
new_base = &new_cpu_base->clock_base[basenum];
if (base != new_base) {
/*
* We are trying to move timer to new_base.
* 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(hrtimer_callback_running(timer)))
return base;
/* See the comment in lock_hrtimer_base() */
timer->base = &migration_base;
raw_spin_unlock(&base->cpu_base->lock);
raw_spin_lock(&new_base->cpu_base->lock);
if (new_cpu_base != this_cpu_base &&
hrtimer_check_target(timer, new_base)) {
raw_spin_unlock(&new_base->cpu_base->lock);
raw_spin_lock(&base->cpu_base->lock);
new_cpu_base = this_cpu_base;
timer->base = base;
goto again;
}
timer->base = new_base;
} else {
if (new_cpu_base != this_cpu_base &&
hrtimer_check_target(timer, new_base)) {
new_cpu_base = this_cpu_base;
goto again;
}
}
return new_base;
}
#else /* CONFIG_SMP */
static inline struct hrtimer_clock_base *
lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
{
struct hrtimer_clock_base *base = timer->base;
raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
return base;
}
# define switch_hrtimer_base(t, b, p) (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
/*
* Divide a ktime value by a nanosecond value
*/
s64 __ktime_divns(const ktime_t kt, s64 div)
{
int sft = 0;
s64 dclc;
u64 tmp;
dclc = ktime_to_ns(kt);
tmp = dclc < 0 ? -dclc : dclc;
/* Make sure the divisor is less than 2^32: */
while (div >> 32) {
sft++;
div >>= 1;
}
tmp >>= sft;
do_div(tmp, (unsigned long) div);
return dclc < 0 ? -tmp : tmp;
}
EXPORT_SYMBOL_GPL(__ktime_divns);
#endif /* BITS_PER_LONG >= 64 */
/*
* Add two ktime values and do a safety check for overflow:
*/
ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
{
ktime_t res = ktime_add(lhs, rhs);
/*
* We use KTIME_SEC_MAX here, the maximum timeout which we can
* return to user space in a timespec:
*/
if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
res = ktime_set(KTIME_SEC_MAX, 0);
return res;
}
EXPORT_SYMBOL_GPL(ktime_add_safe);
#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
static struct debug_obj_descr hrtimer_debug_descr;
static void *hrtimer_debug_hint(void *addr)
{
return ((struct hrtimer *) addr)->function;
}
/*
* fixup_init is called when:
* - an active object is initialized
*/
static int hrtimer_fixup_init(void *addr, enum debug_obj_state state)
{
struct hrtimer *timer = addr;
switch (state) {
case ODEBUG_STATE_ACTIVE:
hrtimer_cancel(timer);
debug_object_init(timer, &hrtimer_debug_descr);
return 1;
default:
return 0;
}
}
/*
* fixup_activate is called when:
* - an active object is activated
* - an unknown object is activated (might be a statically initialized object)
*/
static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
{
switch (state) {
case ODEBUG_STATE_NOTAVAILABLE:
WARN_ON_ONCE(1);
return 0;
case ODEBUG_STATE_ACTIVE:
WARN_ON(1);
default:
return 0;
}
}
/*
* fixup_free is called when:
* - an active object is freed
*/
static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
{
struct hrtimer *timer = addr;
switch (state) {
case ODEBUG_STATE_ACTIVE:
hrtimer_cancel(timer);
debug_object_free(timer, &hrtimer_debug_descr);
return 1;
default:
return 0;
}
}
static struct debug_obj_descr hrtimer_debug_descr = {
.name = "hrtimer",
.debug_hint = hrtimer_debug_hint,
.fixup_init = hrtimer_fixup_init,
.fixup_activate = hrtimer_fixup_activate,
.fixup_free = hrtimer_fixup_free,
};
static inline void debug_hrtimer_init(struct hrtimer *timer)
{
debug_object_init(timer, &hrtimer_debug_descr);
}
static inline void debug_hrtimer_activate(struct hrtimer *timer)
{
debug_object_activate(timer, &hrtimer_debug_descr);
}
static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
{
debug_object_deactivate(timer, &hrtimer_debug_descr);
}
static inline void debug_hrtimer_free(struct hrtimer *timer)
{
debug_object_free(timer, &hrtimer_debug_descr);
}
static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
enum hrtimer_mode mode);
void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
enum hrtimer_mode mode)
{
debug_object_init_on_stack(timer, &hrtimer_debug_descr);
__hrtimer_init(timer, clock_id, mode);
}
EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
void destroy_hrtimer_on_stack(struct hrtimer *timer)
{
debug_object_free(timer, &hrtimer_debug_descr);
}
#else
static inline void debug_hrtimer_init(struct hrtimer *timer) { }
static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
#endif
static inline void
debug_init(struct hrtimer *timer, clockid_t clockid,
enum hrtimer_mode mode)
{
debug_hrtimer_init(timer);
trace_hrtimer_init(timer, clockid, mode);
}
static inline void debug_activate(struct hrtimer *timer)
{
debug_hrtimer_activate(timer);
trace_hrtimer_start(timer);
}
static inline void debug_deactivate(struct hrtimer *timer)
{
debug_hrtimer_deactivate(timer);
trace_hrtimer_cancel(timer);
}
#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
struct hrtimer *timer)
{
#ifdef CONFIG_HIGH_RES_TIMERS
cpu_base->next_timer = timer;
#endif
}
static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
{
struct hrtimer_clock_base *base = cpu_base->clock_base;
ktime_t expires, expires_next = { .tv64 = KTIME_MAX };
unsigned int active = cpu_base->active_bases;
hrtimer_update_next_timer(cpu_base, NULL);
for (; active; base++, active >>= 1) {
struct timerqueue_node *next;
struct hrtimer *timer;
if (!(active & 0x01))
continue;
next = timerqueue_getnext(&base->active);
timer = container_of(next, struct hrtimer, node);
expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
if (expires.tv64 < expires_next.tv64) {
expires_next = expires;
hrtimer_update_next_timer(cpu_base, timer);
}
}
/*
* clock_was_set() might have changed base->offset of any of
* the clock bases so the result might be negative. Fix it up
* to prevent a false positive in clockevents_program_event().
*/
if (expires_next.tv64 < 0)
expires_next.tv64 = 0;
return expires_next;
}
#endif
static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
{
ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
return ktime_get_update_offsets_now(&base->clock_was_set_seq,
offs_real, offs_boot, offs_tai);
}
/* High resolution timer related functions */
#ifdef CONFIG_HIGH_RES_TIMERS
/*
* High resolution timer enabled ?
*/
static int hrtimer_hres_enabled __read_mostly = 1;
unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
EXPORT_SYMBOL_GPL(hrtimer_resolution);
/*
* Enable / Disable high resolution mode
*/
static int __init setup_hrtimer_hres(char *str)
{
if (!strcmp(str, "off"))
hrtimer_hres_enabled = 0;
else if (!strcmp(str, "on"))
hrtimer_hres_enabled = 1;
else
return 0;
return 1;
}
__setup("highres=", setup_hrtimer_hres);
/*
* hrtimer_high_res_enabled - query, if the highres mode is enabled
*/
static inline int hrtimer_is_hres_enabled(void)
{
return hrtimer_hres_enabled;
}
/*
* Is the high resolution mode active ?
*/
static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
{
return cpu_base->hres_active;
}
static inline int hrtimer_hres_active(void)
{
return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
}
/*
* Reprogram the event source with checking both queues for the
* next event
* Called with interrupts disabled and base->lock held
*/
static void
hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
{
ktime_t expires_next;
if (!cpu_base->hres_active)
return;
expires_next = __hrtimer_get_next_event(cpu_base);
if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
return;
cpu_base->expires_next.tv64 = expires_next.tv64;
/*
* If a hang was detected in the last timer interrupt then we
* leave the hang delay active in the hardware. We want the
* system to make progress. That also prevents the following
* scenario:
* T1 expires 50ms from now
* T2 expires 5s from now
*
* T1 is removed, so this code is called and would reprogram
* the hardware to 5s from now. Any hrtimer_start after that
* will not reprogram the hardware due to hang_detected being
* set. So we'd effectivly block all timers until the T2 event
* fires.
*/
if (cpu_base->hang_detected)
return;
tick_program_event(cpu_base->expires_next, 1);
}
/*
* When a timer is enqueued and expires earlier than the already enqueued
* timers, we have to check, whether it expires earlier than the timer for
* which the clock event device was armed.
*
* Called with interrupts disabled and base->cpu_base.lock held
*/
static void hrtimer_reprogram(struct hrtimer *timer,
struct hrtimer_clock_base *base)
{
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
/*
* If the timer is not on the current cpu, we cannot reprogram
* the other cpus clock event device.
*/
if (base->cpu_base != cpu_base)
return;
/*
* If the hrtimer interrupt is running, then it will
* reevaluate the clock bases and reprogram the clock event
* device. The callbacks are always executed in hard interrupt
* context so we don't need an extra check for a running
* callback.
*/
if (cpu_base->in_hrtirq)
return;
/*
* CLOCK_REALTIME timer might be requested with an absolute
* expiry time which is less than base->offset. Set it to 0.
*/
if (expires.tv64 < 0)
expires.tv64 = 0;
if (expires.tv64 >= cpu_base->expires_next.tv64)
return;
/* Update the pointer to the next expiring timer */
cpu_base->next_timer = timer;
/*
* If a hang was detected in the last timer interrupt then we
* do not schedule a timer which is earlier than the expiry
* which we enforced in the hang detection. We want the system
* to make progress.
*/
if (cpu_base->hang_detected)
return;
/*
* Program the timer hardware. We enforce the expiry for
* events which are already in the past.
*/
cpu_base->expires_next = expires;
tick_program_event(expires, 1);
}
/*
* Initialize the high resolution related parts of cpu_base
*/
static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
{
base->expires_next.tv64 = KTIME_MAX;
base->hres_active = 0;
}
/*
* Retrigger next event is called after clock was set
*
* Called with interrupts disabled via on_each_cpu()
*/
static void retrigger_next_event(void *arg)
{
struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
if (!base->hres_active)
return;
raw_spin_lock(&base->lock);
hrtimer_update_base(base);
hrtimer_force_reprogram(base, 0);
raw_spin_unlock(&base->lock);
}
/*
* Switch to high resolution mode
*/
static void hrtimer_switch_to_hres(void)
{
struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
if (tick_init_highres()) {
printk(KERN_WARNING "Could not switch to high resolution "
"mode on CPU %d\n", base->cpu);
return;
}
base->hres_active = 1;
hrtimer_resolution = HIGH_RES_NSEC;
tick_setup_sched_timer();
/* "Retrigger" the interrupt to get things going */
retrigger_next_event(NULL);
}
static void clock_was_set_work(struct work_struct *work)
{
clock_was_set();
}
static DECLARE_WORK(hrtimer_work, clock_was_set_work);
/*
* Called from timekeeping and resume code to reprogramm the hrtimer
* interrupt device on all cpus.
*/
void clock_was_set_delayed(void)
{
schedule_work(&hrtimer_work);
}
#else
static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *b) { return 0; }
static inline int hrtimer_hres_active(void) { return 0; }
static inline int hrtimer_is_hres_enabled(void) { return 0; }
static inline void hrtimer_switch_to_hres(void) { }
static inline void
hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
static inline int hrtimer_reprogram(struct hrtimer *timer,
struct hrtimer_clock_base *base)
{
return 0;
}
static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
static inline void retrigger_next_event(void *arg) { }
#endif /* CONFIG_HIGH_RES_TIMERS */
/*
* Clock realtime was set
*
* Change the offset of the realtime clock vs. the monotonic
* clock.
*
* We might have to reprogram the high resolution timer interrupt. On
* SMP we call the architecture specific code to retrigger _all_ high
* resolution timer interrupts. On UP we just disable interrupts and
* call the high resolution interrupt code.
*/
void clock_was_set(void)
{
#ifdef CONFIG_HIGH_RES_TIMERS
/* Retrigger the CPU local events everywhere */
on_each_cpu(retrigger_next_event, NULL, 1);
#endif
timerfd_clock_was_set();
}
/*
* During resume we might have to reprogram the high resolution timer
* interrupt on all online CPUs. However, all other CPUs will be
* stopped with IRQs interrupts disabled so the clock_was_set() call
* must be deferred.
*/
void hrtimers_resume(void)
{
WARN_ONCE(!irqs_disabled(),
KERN_INFO "hrtimers_resume() called with IRQs enabled!");
/* Retrigger on the local CPU */
retrigger_next_event(NULL);
/* And schedule a retrigger for all others */
clock_was_set_delayed();
}
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
{
#ifdef CONFIG_TIMER_STATS
if (timer->start_site)
return;
timer->start_site = __builtin_return_address(0);
memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
timer->start_pid = current->pid;
#endif
}
static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
{
#ifdef CONFIG_TIMER_STATS
timer->start_site = NULL;
#endif
}
static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
{
#ifdef CONFIG_TIMER_STATS
if (likely(!timer_stats_active))
return;
timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
timer->function, timer->start_comm, 0);
#endif
}
/*
* Counterpart to lock_hrtimer_base above:
*/
static inline
void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
{
raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
}
/**
* hrtimer_forward - forward the timer expiry
* @timer: hrtimer to forward
* @now: forward past this time
* @interval: the interval to forward
*
* Forward the timer expiry so it will expire in the future.
* 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.
*/
u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
{
u64 orun = 1;
ktime_t delta;
delta = ktime_sub(now, hrtimer_get_expires(timer));
if (delta.tv64 < 0)
return 0;
if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
return 0;
if (interval.tv64 < hrtimer_resolution)
interval.tv64 = hrtimer_resolution;
if (unlikely(delta.tv64 >= interval.tv64)) {
s64 incr = ktime_to_ns(interval);
orun = ktime_divns(delta, incr);
hrtimer_add_expires_ns(timer, incr * orun);
if (hrtimer_get_expires_tv64(timer) > now.tv64)
return orun;
/*
* This (and the ktime_add() below) is the
* correction for exact:
*/
orun++;
}
hrtimer_add_expires(timer, interval);
return orun;
}
EXPORT_SYMBOL_GPL(hrtimer_forward);
/*
* 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.
*
* Returns 1 when the new timer is the leftmost timer in the tree.
*/
static int enqueue_hrtimer(struct hrtimer *timer,
struct hrtimer_clock_base *base)
{
debug_activate(timer);
base->cpu_base->active_bases |= 1 << base->index;
timer->state = HRTIMER_STATE_ENQUEUED;
return timerqueue_add(&base->active, &timer->node);
}
/*
* __remove_hrtimer - internal function to remove a timer
*
* Caller must hold the base lock.
*
* High resolution timer mode reprograms the clock event device when the
* timer is the one which expires next. The caller can disable this by setting
* reprogram to zero. This is useful, when the context does a reprogramming
* anyway (e.g. timer interrupt)
*/
static void __remove_hrtimer(struct hrtimer *timer,
struct hrtimer_clock_base *base,
unsigned long newstate, int reprogram)
{
struct hrtimer_cpu_base *cpu_base = base->cpu_base;
unsigned int state = timer->state;
timer->state = newstate;
if (!(state & HRTIMER_STATE_ENQUEUED))
return;
if (!timerqueue_del(&base->active, &timer->node))
cpu_base->active_bases &= ~(1 << base->index);
#ifdef CONFIG_HIGH_RES_TIMERS
/*
* Note: If reprogram is false we do not update
* cpu_base->next_timer. This happens when we remove the first
* timer on a remote cpu. No harm as we never dereference
* cpu_base->next_timer. So the worst thing what can happen is
* an superflous call to hrtimer_force_reprogram() on the
* remote cpu later on if the same timer gets enqueued again.
*/
if (reprogram && timer == cpu_base->next_timer)
hrtimer_force_reprogram(cpu_base, 1);
#endif
}
/*
* remove hrtimer, called with base lock held
*/
static inline int
remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
{
if (hrtimer_is_queued(timer)) {
unsigned long state = timer->state;
int reprogram;
/*
* Remove the timer and force reprogramming when high
* resolution mode is active and the timer is on the current
* CPU. If we remove a timer on another CPU, reprogramming is
* skipped. The interrupt event on this CPU is fired and
* reprogramming happens in the interrupt handler. This is a
* rare case and less expensive than a smp call.
*/
debug_deactivate(timer);
timer_stats_hrtimer_clear_start_info(timer);
reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
if (!restart)
state = HRTIMER_STATE_INACTIVE;
__remove_hrtimer(timer, base, state, reprogram);
return 1;
}
return 0;
}
/**
* hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
* @timer: the timer to be added
* @tim: expiry time
* @delta_ns: "slack" range for the timer
* @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
* relative (HRTIMER_MODE_REL)
*/
void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
unsigned long delta_ns, const enum hrtimer_mode mode)
{
struct hrtimer_clock_base *base, *new_base;
unsigned long flags;
int leftmost;
base = lock_hrtimer_base(timer, &flags);
/* Remove an active timer from the queue: */
remove_hrtimer(timer, base, true);
if (mode & HRTIMER_MODE_REL) {
tim = ktime_add_safe(tim, base->get_time());
/*
* CONFIG_TIME_LOW_RES is a temporary way for architectures
* to signal that they simply return xtime in
* do_gettimeoffset(). In this case we want to round up by
* resolution when starting a relative timer, to avoid short
* timeouts. This will go away with the GTOD framework.
*/
#ifdef CONFIG_TIME_LOW_RES
tim = ktime_add_safe(tim, ktime_set(0, hrtimer_resolution));
#endif
}
hrtimer_set_expires_range_ns(timer, tim, delta_ns);
/* Switch the timer base, if necessary: */
new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
timer_stats_hrtimer_set_start_info(timer);
leftmost = enqueue_hrtimer(timer, new_base);
if (!leftmost)
goto unlock;
if (!hrtimer_is_hres_active(timer)) {
/*
* Kick to reschedule the next tick to handle the new timer
* on dynticks target.
*/
if (new_base->cpu_base->nohz_active)
wake_up_nohz_cpu(new_base->cpu_base->cpu);
} else {
hrtimer_reprogram(timer, new_base);
}
unlock:
unlock_hrtimer_base(timer, &flags);
}
EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
/**
* 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
* cannot be stopped
*/
int hrtimer_try_to_cancel(struct hrtimer *timer)
{
struct hrtimer_clock_base *base;
unsigned long flags;
int ret = -1;
/*
* Check lockless first. If the timer is not active (neither
* enqueued nor running the callback, nothing to do here. The
* base lock does not serialize against a concurrent enqueue,
* so we can avoid taking it.
*/
if (!hrtimer_active(timer))
return 0;
base = lock_hrtimer_base(timer, &flags);
if (!hrtimer_callback_running(timer))
ret = remove_hrtimer(timer, base, false);
unlock_hrtimer_base(timer, &flags);
return ret;
}
EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
/**
* 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;
cpu_relax();
}
}
EXPORT_SYMBOL_GPL(hrtimer_cancel);
/**
* hrtimer_get_remaining - get remaining time for the timer
* @timer: the timer to read
*/
ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
{
unsigned long flags;
ktime_t rem;
lock_hrtimer_base(timer, &flags);
rem = hrtimer_expires_remaining(timer);
unlock_hrtimer_base(timer, &flags);
return rem;
}
EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
#ifdef CONFIG_NO_HZ_COMMON
/**
* hrtimer_get_next_event - get the time until next expiry event
*
* Returns the next expiry time or KTIME_MAX if no timer is pending.
*/
u64 hrtimer_get_next_event(void)
{
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
u64 expires = KTIME_MAX;
unsigned long flags;
raw_spin_lock_irqsave(&cpu_base->lock, flags);
if (!__hrtimer_hres_active(cpu_base))
expires = __hrtimer_get_next_event(cpu_base).tv64;
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
return expires;
}
#endif
static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
enum hrtimer_mode mode)
{
struct hrtimer_cpu_base *cpu_base;
int base;
memset(timer, 0, sizeof(struct hrtimer));
cpu_base = raw_cpu_ptr(&hrtimer_bases);
if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
clock_id = CLOCK_MONOTONIC;
base = hrtimer_clockid_to_base(clock_id);
timer->base = &cpu_base->clock_base[base];
timerqueue_init(&timer->node);
#ifdef CONFIG_TIMER_STATS
timer->start_site = NULL;
timer->start_pid = -1;
memset(timer->start_comm, 0, TASK_COMM_LEN);
#endif
}
/**
* hrtimer_init - initialize a timer to the given clock
* @timer: the timer to be initialized
* @clock_id: the clock to be used
* @mode: timer mode abs/rel
*/
void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
enum hrtimer_mode mode)
{
debug_init(timer, clock_id, mode);
__hrtimer_init(timer, clock_id, mode);
}
EXPORT_SYMBOL_GPL(hrtimer_init);
/*
* 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.
*
* It is important for this function to not return a false negative.
*/
bool hrtimer_active(const struct hrtimer *timer)
{
struct hrtimer_cpu_base *cpu_base;
unsigned int seq;
do {
cpu_base = READ_ONCE(timer->base->cpu_base);
seq = raw_read_seqcount_begin(&cpu_base->seq);
if (timer->state != HRTIMER_STATE_INACTIVE ||
cpu_base->running == timer)
return true;
} while (read_seqcount_retry(&cpu_base->seq, seq) ||
cpu_base != READ_ONCE(timer->base->cpu_base));
return false;
}
EXPORT_SYMBOL_GPL(hrtimer_active);
/*
* The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
* distinct sections:
*
* - queued: the timer is queued
* - callback: the timer is being ran
* - post: the timer is inactive or (re)queued
*
* On the read side we ensure we observe timer->state and cpu_base->running
* from the same section, if anything changed while we looked at it, we retry.
* This includes timer->base changing because sequence numbers alone are
* insufficient for that.
*
* The sequence numbers are required because otherwise we could still observe
* a false negative if the read side got smeared over multiple consequtive
* __run_hrtimer() invocations.
*/
static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
struct hrtimer_clock_base *base,
struct hrtimer *timer, ktime_t *now)
{
enum hrtimer_restart (*fn)(struct hrtimer *);
int restart;
lockdep_assert_held(&cpu_base->lock);
debug_deactivate(timer);
cpu_base->running = timer;
/*
* Separate the ->running assignment from the ->state assignment.
*
* As with a regular write barrier, this ensures the read side in
* hrtimer_active() cannot observe cpu_base->running == NULL &&
* timer->state == INACTIVE.
*/
raw_write_seqcount_barrier(&cpu_base->seq);
__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
timer_stats_account_hrtimer(timer);
fn = timer->function;
/*
* Because we run timers from hardirq context, there is no chance
* they get migrated to another cpu, therefore its safe to unlock
* the timer base.
*/
raw_spin_unlock(&cpu_base->lock);
trace_hrtimer_expire_entry(timer, now);
restart = fn(timer);
trace_hrtimer_expire_exit(timer);
raw_spin_lock(&cpu_base->lock);
/*
* Note: We clear the running state after enqueue_hrtimer and
* we do not reprogramm the event hardware. Happens either in
* hrtimer_start_range_ns() or in hrtimer_interrupt()
*
* Note: Because we dropped the cpu_base->lock above,
* hrtimer_start_range_ns() can have popped in and enqueued the timer
* for us already.
*/
if (restart != HRTIMER_NORESTART &&
!(timer->state & HRTIMER_STATE_ENQUEUED))
enqueue_hrtimer(timer, base);
/*
* Separate the ->running assignment from the ->state assignment.
*
* As with a regular write barrier, this ensures the read side in
* hrtimer_active() cannot observe cpu_base->running == NULL &&
* timer->state == INACTIVE.
*/
raw_write_seqcount_barrier(&cpu_base->seq);
WARN_ON_ONCE(cpu_base->running != timer);
cpu_base->running = NULL;
}
static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
{
struct hrtimer_clock_base *base = cpu_base->clock_base;
unsigned int active = cpu_base->active_bases;
for (; active; base++, active >>= 1) {
struct timerqueue_node *node;
ktime_t basenow;
if (!(active & 0x01))
continue;
basenow = ktime_add(now, base->offset);
while ((node = timerqueue_getnext(&base->active))) {
struct hrtimer *timer;
timer = container_of(node, struct hrtimer, node);
/*
* The immediate goal for using the softexpires is
* minimizing wakeups, not running timers at the
* earliest interrupt after their soft expiration.
* This allows us to avoid using a Priority Search
* Tree, which can answer a stabbing querry for
* overlapping intervals and instead use the simple
* BST we already have.
* We don't add extra wakeups by delaying timers that
* are right-of a not yet expired timer, because that
* timer will have to trigger a wakeup anyway.
*/
if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer))
break;
__run_hrtimer(cpu_base, base, timer, &basenow);
}
}
}
#ifdef CONFIG_HIGH_RES_TIMERS
/*
* High resolution timer interrupt
* Called with interrupts disabled
*/
void hrtimer_interrupt(struct clock_event_device *dev)
{
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
ktime_t expires_next, now, entry_time, delta;
int retries = 0;
BUG_ON(!cpu_base->hres_active);
cpu_base->nr_events++;
dev->next_event.tv64 = KTIME_MAX;
raw_spin_lock(&cpu_base->lock);
entry_time = now = hrtimer_update_base(cpu_base);
retry:
cpu_base->in_hrtirq = 1;
/*
* We set expires_next to KTIME_MAX here with cpu_base->lock
* held to prevent that a timer is enqueued in our queue via
* the migration code. This does not affect enqueueing of
* timers which run their callback and need to be requeued on
* this CPU.
*/
cpu_base->expires_next.tv64 = KTIME_MAX;
__hrtimer_run_queues(cpu_base, now);
/* Reevaluate the clock bases for the next expiry */
expires_next = __hrtimer_get_next_event(cpu_base);
/*
* Store the new expiry value so the migration code can verify
* against it.
*/
cpu_base->expires_next = expires_next;
cpu_base->in_hrtirq = 0;
raw_spin_unlock(&cpu_base->lock);
/* Reprogramming necessary ? */
if (!tick_program_event(expires_next, 0)) {
cpu_base->hang_detected = 0;
return;
}
/*
* The next timer was already expired due to:
* - tracing
* - long lasting callbacks
* - being scheduled away when running in a VM
*
* We need to prevent that we loop forever in the hrtimer
* interrupt routine. We give it 3 attempts to avoid
* overreacting on some spurious event.
*
* Acquire base lock for updating the offsets and retrieving
* the current time.
*/
raw_spin_lock(&cpu_base->lock);
now = hrtimer_update_base(cpu_base);
cpu_base->nr_retries++;
if (++retries < 3)
goto retry;
/*
* Give the system a chance to do something else than looping
* here. We stored the entry time, so we know exactly how long
* we spent here. We schedule the next event this amount of
* time away.
*/
cpu_base->nr_hangs++;
cpu_base->hang_detected = 1;
raw_spin_unlock(&cpu_base->lock);
delta = ktime_sub(now, entry_time);
if ((unsigned int)delta.tv64 > cpu_base->max_hang_time)
cpu_base->max_hang_time = (unsigned int) delta.tv64;
/*
* Limit it to a sensible value as we enforce a longer
* delay. Give the CPU at least 100ms to catch up.
*/
if (delta.tv64 > 100 * NSEC_PER_MSEC)
expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
else
expires_next = ktime_add(now, delta);
tick_program_event(expires_next, 1);
printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
ktime_to_ns(delta));
}
/*
* local version of hrtimer_peek_ahead_timers() called with interrupts
* disabled.
*/
static inline void __hrtimer_peek_ahead_timers(void)
{
struct tick_device *td;
if (!hrtimer_hres_active())
return;
td = this_cpu_ptr(&tick_cpu_device);
if (td && td->evtdev)
hrtimer_interrupt(td->evtdev);
}
#else /* CONFIG_HIGH_RES_TIMERS */
static inline void __hrtimer_peek_ahead_timers(void) { }
#endif /* !CONFIG_HIGH_RES_TIMERS */
/*
* Called from run_local_timers in hardirq context every jiffy
*/
void hrtimer_run_queues(void)
{
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
ktime_t now;
if (__hrtimer_hres_active(cpu_base))
return;
/*
* This _is_ ugly: We have to check periodically, whether we
* can switch to highres and / or nohz mode. The clocksource
* switch happens with xtime_lock held. Notification from
* there only sets the check bit in the tick_oneshot code,
* otherwise we might deadlock vs. xtime_lock.
*/
if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
hrtimer_switch_to_hres();
return;
}
raw_spin_lock(&cpu_base->lock);
now = hrtimer_update_base(cpu_base);
__hrtimer_run_queues(cpu_base, now);
raw_spin_unlock(&cpu_base->lock);
}
/*
* Sleep related functions:
*/
static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
{
struct hrtimer_sleeper *t =
container_of(timer, struct hrtimer_sleeper, timer);
struct task_struct *task = t->task;
t->task = NULL;
if (task)
wake_up_process(task);
return HRTIMER_NORESTART;
}
void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
{
sl->timer.function = hrtimer_wakeup;
sl->task = task;
}
EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
{
hrtimer_init_sleeper(t, current);
do {
set_current_state(TASK_INTERRUPTIBLE);
hrtimer_start_expires(&t->timer, mode);
if (likely(t->task))
freezable_schedule();
hrtimer_cancel(&t->timer);
mode = HRTIMER_MODE_ABS;
} while (t->task && !signal_pending(current));
__set_current_state(TASK_RUNNING);
return t->task == NULL;
}
static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
{
struct timespec rmt;
ktime_t rem;
rem = hrtimer_expires_remaining(timer);
if (rem.tv64 <= 0)
return 0;
rmt = ktime_to_timespec(rem);
if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
return -EFAULT;
return 1;
}
long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
{
struct hrtimer_sleeper t;
struct timespec __user *rmtp;
int ret = 0;
hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
HRTIMER_MODE_ABS);
hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
if (do_nanosleep(&t, HRTIMER_MODE_ABS))
goto out;
rmtp = restart->nanosleep.rmtp;
if (rmtp) {
ret = update_rmtp(&t.timer, rmtp);
if (ret <= 0)
goto out;
}
/* The other values in restart are already filled in */
ret = -ERESTART_RESTARTBLOCK;
out:
destroy_hrtimer_on_stack(&t.timer);
return ret;
}
long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
const enum hrtimer_mode mode, const clockid_t clockid)
{
struct restart_block *restart;
struct hrtimer_sleeper t;
int ret = 0;
unsigned long slack;
slack = current->timer_slack_ns;
if (dl_task(current) || rt_task(current))
slack = 0;
hrtimer_init_on_stack(&t.timer, clockid, mode);
hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
if (do_nanosleep(&t, mode))
goto out;
/* Absolute timers do not update the rmtp value and restart: */
if (mode == HRTIMER_MODE_ABS) {
ret = -ERESTARTNOHAND;
goto out;
}
if (rmtp) {
ret = update_rmtp(&t.timer, rmtp);
if (ret <= 0)
goto out;
}
restart = ¤t->restart_block;
restart->fn = hrtimer_nanosleep_restart;
restart->nanosleep.clockid = t.timer.base->clockid;
restart->nanosleep.rmtp = rmtp;
restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
ret = -ERESTART_RESTARTBLOCK;
out:
destroy_hrtimer_on_stack(&t.timer);
return ret;
}
SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
struct timespec __user *, rmtp)
{
struct timespec tu;
if (copy_from_user(&tu, rqtp, sizeof(tu)))
return -EFAULT;
if (!timespec_valid(&tu))
return -EINVAL;
return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
}
/*
* Functions related to boot-time initialization:
*/
static void init_hrtimers_cpu(int cpu)
{
struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
int i;
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
cpu_base->clock_base[i].cpu_base = cpu_base;
timerqueue_init_head(&cpu_base->clock_base[i].active);
}
cpu_base->cpu = cpu;
hrtimer_init_hres(cpu_base);
}
#ifdef CONFIG_HOTPLUG_CPU
static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
struct hrtimer_clock_base *new_base)
{
struct hrtimer *timer;
struct timerqueue_node *node;
while ((node = timerqueue_getnext(&old_base->active))) {
timer = container_of(node, struct hrtimer, node);
BUG_ON(hrtimer_callback_running(timer));
debug_deactivate(timer);
/*
* Mark it as ENQUEUED not INACTIVE otherwise the
* timer could be seen as !active and just vanish away
* under us on another CPU
*/
__remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
timer->base = new_base;
/*
* Enqueue the timers on the new cpu. This does not
* reprogram the event device in case the timer
* expires before the earliest on this CPU, but we run
* hrtimer_interrupt after we migrated everything to
* sort out already expired timers and reprogram the
* event device.
*/
enqueue_hrtimer(timer, new_base);
}
}
static void migrate_hrtimers(int scpu)
{
struct hrtimer_cpu_base *old_base, *new_base;
int i;
BUG_ON(cpu_online(scpu));
tick_cancel_sched_timer(scpu);
local_irq_disable();
old_base = &per_cpu(hrtimer_bases, scpu);
new_base = this_cpu_ptr(&hrtimer_bases);
/*
* The caller is globally serialized and nobody else
* takes two locks at once, deadlock is not possible.
*/
raw_spin_lock(&new_base->lock);
raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
migrate_hrtimer_list(&old_base->clock_base[i],
&new_base->clock_base[i]);
}
raw_spin_unlock(&old_base->lock);
raw_spin_unlock(&new_base->lock);
/* Check, if we got expired work to do */
__hrtimer_peek_ahead_timers();
local_irq_enable();
}
#endif /* CONFIG_HOTPLUG_CPU */
static int hrtimer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
int scpu = (long)hcpu;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
init_hrtimers_cpu(scpu);
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DEAD:
case CPU_DEAD_FROZEN:
migrate_hrtimers(scpu);
break;
#endif
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block 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);
}
/**
* schedule_hrtimeout_range_clock - sleep until timeout
* @expires: timeout value (ktime_t)
* @delta: slack in expires timeout (ktime_t)
* @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
* @clock: timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
*/
int __sched
schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta,
const enum hrtimer_mode mode, int clock)
{
struct hrtimer_sleeper t;
/*
* Optimize when a zero timeout value is given. It does not
* matter whether this is an absolute or a relative time.
*/
if (expires && !expires->tv64) {
__set_current_state(TASK_RUNNING);
return 0;
}
/*
* A NULL parameter means "infinite"
*/
if (!expires) {
schedule();
return -EINTR;
}
hrtimer_init_on_stack(&t.timer, clock, mode);
hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
hrtimer_init_sleeper(&t, current);
hrtimer_start_expires(&t.timer, mode);
if (likely(t.task))
schedule();
hrtimer_cancel(&t.timer);
destroy_hrtimer_on_stack(&t.timer);
__set_current_state(TASK_RUNNING);
return !t.task ? 0 : -EINTR;
}
/**
* schedule_hrtimeout_range - sleep until timeout
* @expires: timeout value (ktime_t)
* @delta: slack in expires timeout (ktime_t)
* @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
*
* Make the current task sleep until the given expiry time has
* elapsed. The routine will return immediately unless
* the current task state has been set (see set_current_state()).
*
* The @delta argument gives the kernel the freedom to schedule the
* actual wakeup to a time that is both power and performance friendly.
* The kernel give the normal best effort behavior for "@expires+@delta",
* but may decide to fire the timer earlier, but no earlier than @expires.
*
* You can set the task state as follows -
*
* %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
* pass before the routine returns.
*
* %TASK_INTERRUPTIBLE - the routine may return early if a signal is
* delivered to the current task.
*
* The current task state is guaranteed to be TASK_RUNNING when this
* routine returns.
*
* Returns 0 when the timer has expired otherwise -EINTR
*/
int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
const enum hrtimer_mode mode)
{
return schedule_hrtimeout_range_clock(expires, delta, mode,
CLOCK_MONOTONIC);
}
EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
/**
* schedule_hrtimeout - sleep until timeout
* @expires: timeout value (ktime_t)
* @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
*
* Make the current task sleep until the given expiry time has
* elapsed. The routine will return immediately unless
* the current task state has been set (see set_current_state()).
*
* You can set the task state as follows -
*
* %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
* pass before the routine returns.
*
* %TASK_INTERRUPTIBLE - the routine may return early if a signal is
* delivered to the current task.
*
* The current task state is guaranteed to be TASK_RUNNING when this
* routine returns.
*
* Returns 0 when the timer has expired otherwise -EINTR
*/
int __sched schedule_hrtimeout(ktime_t *expires,
const enum hrtimer_mode mode)
{
return schedule_hrtimeout_range(expires, 0, mode);
}
EXPORT_SYMBOL_GPL(schedule_hrtimeout);