// SPDX-License-Identifier: GPL-2.0
|
/*
|
* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
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*
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* High-resolution kernel timers
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*
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* In contrast to the low-resolution timeout API, aka timer wheel,
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* hrtimers provide finer resolution and accuracy depending on system
|
* configuration and capabilities.
|
*
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* Started by: Thomas Gleixner and Ingo Molnar
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*
|
* Credits:
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* Based on the original timer wheel code
|
*
|
* Help, testing, suggestions, bugfixes, improvements were
|
* provided by:
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*
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* George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
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* et. al.
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*/
|
|
#include <linux/cpu.h>
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#include <linux/export.h>
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#include <linux/percpu.h>
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#include <linux/hrtimer.h>
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#include <linux/notifier.h>
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#include <linux/syscalls.h>
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#include <linux/interrupt.h>
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#include <linux/tick.h>
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#include <linux/err.h>
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#include <linux/debugobjects.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/sysctl.h>
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#include <linux/sched/rt.h>
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#include <linux/sched/deadline.h>
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#include <linux/sched/nohz.h>
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#include <linux/sched/debug.h>
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#include <linux/timer.h>
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#include <linux/freezer.h>
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#include <linux/compat.h>
|
|
#include <linux/uaccess.h>
|
|
#include <trace/events/timer.h>
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|
#include "tick-internal.h"
|
|
/*
|
* Masks for selecting the soft and hard context timers from
|
* cpu_base->active
|
*/
|
#define MASK_SHIFT (HRTIMER_BASE_MONOTONIC_SOFT)
|
#define HRTIMER_ACTIVE_HARD ((1U << MASK_SHIFT) - 1)
|
#define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT)
|
#define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
|
|
/*
|
* 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),
|
.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,
|
},
|
{
|
.index = HRTIMER_BASE_MONOTONIC_SOFT,
|
.clockid = CLOCK_MONOTONIC,
|
.get_time = &ktime_get,
|
},
|
{
|
.index = HRTIMER_BASE_REALTIME_SOFT,
|
.clockid = CLOCK_REALTIME,
|
.get_time = &ktime_get_real,
|
},
|
{
|
.index = HRTIMER_BASE_BOOTTIME_SOFT,
|
.clockid = CLOCK_BOOTTIME,
|
.get_time = &ktime_get_boottime,
|
},
|
{
|
.index = HRTIMER_BASE_TAI_SOFT,
|
.clockid = CLOCK_TAI,
|
.get_time = &ktime_get_clocktai,
|
},
|
}
|
};
|
|
static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
|
/* Make sure we catch unsupported clockids */
|
[0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
|
|
[CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
|
[CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
|
[CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
|
[CLOCK_TAI] = HRTIMER_BASE_TAI,
|
};
|
|
/*
|
* 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 = {
|
.clock_base = { {
|
.cpu_base = &migration_cpu_base,
|
.seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
|
&migration_cpu_base.lock),
|
}, },
|
};
|
|
#define migration_base migration_cpu_base.clock_base[0]
|
|
static inline bool is_migration_base(struct hrtimer_clock_base *base)
|
{
|
return base == &migration_base;
|
}
|
|
/*
|
* 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 = READ_ONCE(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();
|
}
|
}
|
|
/*
|
* We do not migrate the timer when it is expiring before the next
|
* event on the target cpu. When high resolution is enabled, we cannot
|
* reprogram the target cpu hardware and we would cause it to fire
|
* late. To keep it simple, we handle the high resolution enabled and
|
* disabled case similar.
|
*
|
* Called with cpu_base->lock of target cpu held.
|
*/
|
static int
|
hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
|
{
|
ktime_t expires;
|
|
expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
|
return expires < new_base->cpu_base->expires_next;
|
}
|
|
static inline
|
struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
|
int pinned)
|
{
|
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
|
if (static_branch_likely(&timers_migration_enabled) && !pinned)
|
return &per_cpu(hrtimer_bases, get_nohz_timer_target());
|
#endif
|
return base;
|
}
|
|
/*
|
* 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) {
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/*
|
* 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() */
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WRITE_ONCE(timer->base, &migration_base);
|
raw_spin_unlock(&base->cpu_base->lock);
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raw_spin_lock(&new_base->cpu_base->lock);
|
|
if (new_cpu_base != this_cpu_base &&
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hrtimer_check_target(timer, new_base)) {
|
raw_spin_unlock(&new_base->cpu_base->lock);
|
raw_spin_lock(&base->cpu_base->lock);
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new_cpu_base = this_cpu_base;
|
WRITE_ONCE(timer->base, base);
|
goto again;
|
}
|
WRITE_ONCE(timer->base, new_base);
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} else {
|
if (new_cpu_base != this_cpu_base &&
|
hrtimer_check_target(timer, new_base)) {
|
new_cpu_base = this_cpu_base;
|
goto again;
|
}
|
}
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return new_base;
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}
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|
#else /* CONFIG_SMP */
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|
static inline bool is_migration_base(struct hrtimer_clock_base *base)
|
{
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return false;
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}
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|
static inline struct hrtimer_clock_base *
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lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
|
{
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struct hrtimer_clock_base *base = timer->base;
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raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
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|
return base;
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}
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# define switch_hrtimer_base(t, b, p) (b)
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|
#endif /* !CONFIG_SMP */
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/*
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* Functions for the union type storage format of ktime_t which are
|
* too large for inlining:
|
*/
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#if BITS_PER_LONG < 64
|
/*
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* Divide a ktime value by a nanosecond value
|
*/
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s64 __ktime_divns(const ktime_t kt, s64 div)
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{
|
int sft = 0;
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s64 dclc;
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u64 tmp;
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|
dclc = ktime_to_ns(kt);
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tmp = dclc < 0 ? -dclc : dclc;
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/* Make sure the divisor is less than 2^32: */
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while (div >> 32) {
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sft++;
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div >>= 1;
|
}
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tmp >>= sft;
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do_div(tmp, (u32) div);
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return dclc < 0 ? -tmp : tmp;
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}
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EXPORT_SYMBOL_GPL(__ktime_divns);
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#endif /* BITS_PER_LONG >= 64 */
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|
/*
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* Add two ktime values and do a safety check for overflow:
|
*/
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ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
|
{
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ktime_t res = ktime_add_unsafe(lhs, rhs);
|
|
/*
|
* We use KTIME_SEC_MAX here, the maximum timeout which we can
|
* return to user space in a timespec:
|
*/
|
if (res < 0 || res < lhs || res < rhs)
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res = ktime_set(KTIME_SEC_MAX, 0);
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|
return res;
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}
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EXPORT_SYMBOL_GPL(ktime_add_safe);
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#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
|
|
static const struct debug_obj_descr hrtimer_debug_descr;
|
|
static void *hrtimer_debug_hint(void *addr)
|
{
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return ((struct hrtimer *) addr)->function;
|
}
|
|
/*
|
* fixup_init is called when:
|
* - an active object is initialized
|
*/
|
static bool 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 true;
|
default:
|
return false;
|
}
|
}
|
|
/*
|
* fixup_activate is called when:
|
* - an active object is activated
|
* - an unknown non-static object is activated
|
*/
|
static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
|
{
|
switch (state) {
|
case ODEBUG_STATE_ACTIVE:
|
WARN_ON(1);
|
fallthrough;
|
default:
|
return false;
|
}
|
}
|
|
/*
|
* fixup_free is called when:
|
* - an active object is freed
|
*/
|
static bool 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 true;
|
default:
|
return false;
|
}
|
}
|
|
static const 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,
|
enum hrtimer_mode mode)
|
{
|
debug_object_activate(timer, &hrtimer_debug_descr);
|
}
|
|
static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
|
{
|
debug_object_deactivate(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);
|
|
static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
|
clockid_t clock_id, enum hrtimer_mode mode);
|
|
void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
|
clockid_t clock_id, enum hrtimer_mode mode)
|
{
|
debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
|
__hrtimer_init_sleeper(sl, clock_id, mode);
|
}
|
EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
|
|
void destroy_hrtimer_on_stack(struct hrtimer *timer)
|
{
|
debug_object_free(timer, &hrtimer_debug_descr);
|
}
|
EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
|
|
#else
|
|
static inline void debug_hrtimer_init(struct hrtimer *timer) { }
|
static inline void debug_hrtimer_activate(struct hrtimer *timer,
|
enum hrtimer_mode mode) { }
|
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,
|
enum hrtimer_mode mode)
|
{
|
debug_hrtimer_activate(timer, mode);
|
trace_hrtimer_start(timer, mode);
|
}
|
|
static inline void debug_deactivate(struct hrtimer *timer)
|
{
|
debug_hrtimer_deactivate(timer);
|
trace_hrtimer_cancel(timer);
|
}
|
|
static struct hrtimer_clock_base *
|
__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
|
{
|
unsigned int idx;
|
|
if (!*active)
|
return NULL;
|
|
idx = __ffs(*active);
|
*active &= ~(1U << idx);
|
|
return &cpu_base->clock_base[idx];
|
}
|
|
#define for_each_active_base(base, cpu_base, active) \
|
while ((base = __next_base((cpu_base), &(active))))
|
|
static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
|
const struct hrtimer *exclude,
|
unsigned int active,
|
ktime_t expires_next)
|
{
|
struct hrtimer_clock_base *base;
|
ktime_t expires;
|
|
for_each_active_base(base, cpu_base, active) {
|
struct timerqueue_node *next;
|
struct hrtimer *timer;
|
|
next = timerqueue_getnext(&base->active);
|
timer = container_of(next, struct hrtimer, node);
|
if (timer == exclude) {
|
/* Get to the next timer in the queue. */
|
next = timerqueue_iterate_next(next);
|
if (!next)
|
continue;
|
|
timer = container_of(next, struct hrtimer, node);
|
}
|
expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
|
if (expires < expires_next) {
|
expires_next = expires;
|
|
/* Skip cpu_base update if a timer is being excluded. */
|
if (exclude)
|
continue;
|
|
if (timer->is_soft)
|
cpu_base->softirq_next_timer = timer;
|
else
|
cpu_base->next_timer = 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 < 0)
|
expires_next = 0;
|
return expires_next;
|
}
|
|
/*
|
* Recomputes cpu_base::*next_timer and returns the earliest expires_next
|
* but does not set cpu_base::*expires_next, that is done by
|
* hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
|
* cpu_base::*expires_next right away, reprogramming logic would no longer
|
* work.
|
*
|
* When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
|
* those timers will get run whenever the softirq gets handled, at the end of
|
* hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
|
*
|
* Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
|
* The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
|
* softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
|
*
|
* @active_mask must be one of:
|
* - HRTIMER_ACTIVE_ALL,
|
* - HRTIMER_ACTIVE_SOFT, or
|
* - HRTIMER_ACTIVE_HARD.
|
*/
|
static ktime_t
|
__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
|
{
|
unsigned int active;
|
struct hrtimer *next_timer = NULL;
|
ktime_t expires_next = KTIME_MAX;
|
|
if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
|
active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
|
cpu_base->softirq_next_timer = NULL;
|
expires_next = __hrtimer_next_event_base(cpu_base, NULL,
|
active, KTIME_MAX);
|
|
next_timer = cpu_base->softirq_next_timer;
|
}
|
|
if (active_mask & HRTIMER_ACTIVE_HARD) {
|
active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
|
cpu_base->next_timer = next_timer;
|
expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
|
expires_next);
|
}
|
|
return expires_next;
|
}
|
|
static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
|
{
|
ktime_t expires_next, soft = KTIME_MAX;
|
|
/*
|
* If the soft interrupt has already been activated, ignore the
|
* soft bases. They will be handled in the already raised soft
|
* interrupt.
|
*/
|
if (!cpu_base->softirq_activated) {
|
soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
|
/*
|
* Update the soft expiry time. clock_settime() might have
|
* affected it.
|
*/
|
cpu_base->softirq_expires_next = soft;
|
}
|
|
expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
|
/*
|
* If a softirq timer is expiring first, update cpu_base->next_timer
|
* and program the hardware with the soft expiry time.
|
*/
|
if (expires_next > soft) {
|
cpu_base->next_timer = cpu_base->softirq_next_timer;
|
expires_next = soft;
|
}
|
|
return expires_next;
|
}
|
|
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;
|
|
ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
|
offs_real, offs_boot, offs_tai);
|
|
base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
|
base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
|
base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
|
|
return now;
|
}
|
|
/*
|
* Is the high resolution mode active ?
|
*/
|
static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
|
{
|
return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
|
cpu_base->hres_active : 0;
|
}
|
|
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;
|
|
expires_next = hrtimer_update_next_event(cpu_base);
|
|
if (skip_equal && expires_next == cpu_base->expires_next)
|
return;
|
|
cpu_base->expires_next = expires_next;
|
|
/*
|
* If hres is not active, hardware does not have to be
|
* reprogrammed yet.
|
*
|
* 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 (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
|
return;
|
|
tick_program_event(cpu_base->expires_next, 1);
|
}
|
|
/* High resolution timer related functions */
|
#ifdef CONFIG_HIGH_RES_TIMERS
|
|
/*
|
* High resolution timer enabled ?
|
*/
|
static bool hrtimer_hres_enabled __read_mostly = true;
|
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)
|
{
|
return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
|
}
|
|
__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;
|
}
|
|
/*
|
* 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 (!__hrtimer_hres_active(base))
|
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()) {
|
pr_warn("Could not switch to high resolution mode on CPU %u\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);
|
}
|
|
#else
|
|
static inline int hrtimer_is_hres_enabled(void) { return 0; }
|
static inline void hrtimer_switch_to_hres(void) { }
|
static inline void retrigger_next_event(void *arg) { }
|
|
#endif /* CONFIG_HIGH_RES_TIMERS */
|
|
/*
|
* 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, bool reprogram)
|
{
|
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
|
struct hrtimer_clock_base *base = timer->base;
|
ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
|
|
WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
|
|
/*
|
* CLOCK_REALTIME timer might be requested with an absolute
|
* expiry time which is less than base->offset. Set it to 0.
|
*/
|
if (expires < 0)
|
expires = 0;
|
|
if (timer->is_soft) {
|
/*
|
* soft hrtimer could be started on a remote CPU. In this
|
* case softirq_expires_next needs to be updated on the
|
* remote CPU. The soft hrtimer will not expire before the
|
* first hard hrtimer on the remote CPU -
|
* hrtimer_check_target() prevents this case.
|
*/
|
struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
|
|
if (timer_cpu_base->softirq_activated)
|
return;
|
|
if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
|
return;
|
|
timer_cpu_base->softirq_next_timer = timer;
|
timer_cpu_base->softirq_expires_next = expires;
|
|
if (!ktime_before(expires, timer_cpu_base->expires_next) ||
|
!reprogram)
|
return;
|
}
|
|
/*
|
* 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;
|
|
if (expires >= cpu_base->expires_next)
|
return;
|
|
/* Update the pointer to the next expiring timer */
|
cpu_base->next_timer = timer;
|
cpu_base->expires_next = expires;
|
|
/*
|
* If hres is not active, hardware does not have to be
|
* programmed yet.
|
*
|
* 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 (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
|
return;
|
|
/*
|
* Program the timer hardware. We enforce the expiry for
|
* events which are already in the past.
|
*/
|
tick_program_event(expires, 1);
|
}
|
|
/*
|
* 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();
|
}
|
|
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 reprogram the hrtimer
|
* interrupt device on all cpus and to notify timerfd.
|
*/
|
void clock_was_set_delayed(void)
|
{
|
schedule_work(&hrtimer_work);
|
}
|
|
/*
|
* 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)
|
{
|
lockdep_assert_irqs_disabled();
|
/* Retrigger on the local CPU */
|
retrigger_next_event(NULL);
|
/* And schedule a retrigger for all others */
|
clock_was_set_delayed();
|
}
|
|
/*
|
* 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 < 0)
|
return 0;
|
|
if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
|
return 0;
|
|
if (interval < hrtimer_resolution)
|
interval = hrtimer_resolution;
|
|
if (unlikely(delta >= interval)) {
|
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)
|
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,
|
enum hrtimer_mode mode)
|
{
|
debug_activate(timer, mode);
|
|
base->cpu_base->active_bases |= 1 << base->index;
|
|
/* Pairs with the lockless read in hrtimer_is_queued() */
|
WRITE_ONCE(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,
|
u8 newstate, int reprogram)
|
{
|
struct hrtimer_cpu_base *cpu_base = base->cpu_base;
|
u8 state = timer->state;
|
|
/* Pairs with the lockless read in hrtimer_is_queued() */
|
WRITE_ONCE(timer->state, newstate);
|
if (!(state & HRTIMER_STATE_ENQUEUED))
|
return;
|
|
if (!timerqueue_del(&base->active, &timer->node))
|
cpu_base->active_bases &= ~(1 << base->index);
|
|
/*
|
* 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);
|
}
|
|
/*
|
* remove hrtimer, called with base lock held
|
*/
|
static inline int
|
remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
|
bool restart, bool keep_local)
|
{
|
u8 state = timer->state;
|
|
if (state & HRTIMER_STATE_ENQUEUED) {
|
bool 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);
|
reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
|
|
/*
|
* If the timer is not restarted then reprogramming is
|
* required if the timer is local. If it is local and about
|
* to be restarted, avoid programming it twice (on removal
|
* and a moment later when it's requeued).
|
*/
|
if (!restart)
|
state = HRTIMER_STATE_INACTIVE;
|
else
|
reprogram &= !keep_local;
|
|
__remove_hrtimer(timer, base, state, reprogram);
|
return 1;
|
}
|
return 0;
|
}
|
|
static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
|
const enum hrtimer_mode mode)
|
{
|
#ifdef CONFIG_TIME_LOW_RES
|
/*
|
* CONFIG_TIME_LOW_RES indicates that the system has no way to return
|
* granular time values. For relative timers we add hrtimer_resolution
|
* (i.e. one jiffie) to prevent short timeouts.
|
*/
|
timer->is_rel = mode & HRTIMER_MODE_REL;
|
if (timer->is_rel)
|
tim = ktime_add_safe(tim, hrtimer_resolution);
|
#endif
|
return tim;
|
}
|
|
static void
|
hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
|
{
|
ktime_t expires;
|
|
/*
|
* Find the next SOFT expiration.
|
*/
|
expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
|
|
/*
|
* reprogramming needs to be triggered, even if the next soft
|
* hrtimer expires at the same time than the next hard
|
* hrtimer. cpu_base->softirq_expires_next needs to be updated!
|
*/
|
if (expires == KTIME_MAX)
|
return;
|
|
/*
|
* cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
|
* cpu_base->*expires_next is only set by hrtimer_reprogram()
|
*/
|
hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
|
}
|
|
static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
|
u64 delta_ns, const enum hrtimer_mode mode,
|
struct hrtimer_clock_base *base)
|
{
|
struct hrtimer_clock_base *new_base;
|
bool force_local, first;
|
|
/*
|
* If the timer is on the local cpu base and is the first expiring
|
* timer then this might end up reprogramming the hardware twice
|
* (on removal and on enqueue). To avoid that by prevent the
|
* reprogram on removal, keep the timer local to the current CPU
|
* and enforce reprogramming after it is queued no matter whether
|
* it is the new first expiring timer again or not.
|
*/
|
force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
|
force_local &= base->cpu_base->next_timer == timer;
|
|
/*
|
* Remove an active timer from the queue. In case it is not queued
|
* on the current CPU, make sure that remove_hrtimer() updates the
|
* remote data correctly.
|
*
|
* If it's on the current CPU and the first expiring timer, then
|
* skip reprogramming, keep the timer local and enforce
|
* reprogramming later if it was the first expiring timer. This
|
* avoids programming the underlying clock event twice (once at
|
* removal and once after enqueue).
|
*/
|
remove_hrtimer(timer, base, true, force_local);
|
|
if (mode & HRTIMER_MODE_REL)
|
tim = ktime_add_safe(tim, base->get_time());
|
|
tim = hrtimer_update_lowres(timer, tim, mode);
|
|
hrtimer_set_expires_range_ns(timer, tim, delta_ns);
|
|
/* Switch the timer base, if necessary: */
|
if (!force_local) {
|
new_base = switch_hrtimer_base(timer, base,
|
mode & HRTIMER_MODE_PINNED);
|
} else {
|
new_base = base;
|
}
|
|
first = enqueue_hrtimer(timer, new_base, mode);
|
if (!force_local)
|
return first;
|
|
/*
|
* Timer was forced to stay on the current CPU to avoid
|
* reprogramming on removal and enqueue. Force reprogram the
|
* hardware by evaluating the new first expiring timer.
|
*/
|
hrtimer_force_reprogram(new_base->cpu_base, 1);
|
return 0;
|
}
|
|
/**
|
* hrtimer_start_range_ns - (re)start an hrtimer
|
* @timer: the timer to be added
|
* @tim: expiry time
|
* @delta_ns: "slack" range for the timer
|
* @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
|
* relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
|
* softirq based mode is considered for debug purpose only!
|
*/
|
void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
|
u64 delta_ns, const enum hrtimer_mode mode)
|
{
|
struct hrtimer_clock_base *base;
|
unsigned long flags;
|
|
/*
|
* Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
|
* match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
|
* expiry mode because unmarked timers are moved to softirq expiry.
|
*/
|
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
|
WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
|
else
|
WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
|
|
base = lock_hrtimer_base(timer, &flags);
|
|
if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
|
hrtimer_reprogram(timer, true);
|
|
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 executing 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, false);
|
|
unlock_hrtimer_base(timer, &flags);
|
|
return ret;
|
|
}
|
EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
|
|
#ifdef CONFIG_PREEMPT_RT
|
static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
|
{
|
spin_lock_init(&base->softirq_expiry_lock);
|
}
|
|
static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
|
{
|
spin_lock(&base->softirq_expiry_lock);
|
}
|
|
static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
|
{
|
spin_unlock(&base->softirq_expiry_lock);
|
}
|
|
/*
|
* The counterpart to hrtimer_cancel_wait_running().
|
*
|
* If there is a waiter for cpu_base->expiry_lock, then it was waiting for
|
* the timer callback to finish. Drop expiry_lock and reaquire it. That
|
* allows the waiter to acquire the lock and make progress.
|
*/
|
static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
|
unsigned long flags)
|
{
|
if (atomic_read(&cpu_base->timer_waiters)) {
|
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
|
spin_unlock(&cpu_base->softirq_expiry_lock);
|
spin_lock(&cpu_base->softirq_expiry_lock);
|
raw_spin_lock_irq(&cpu_base->lock);
|
}
|
}
|
|
/*
|
* This function is called on PREEMPT_RT kernels when the fast path
|
* deletion of a timer failed because the timer callback function was
|
* running.
|
*
|
* This prevents priority inversion: if the soft irq thread is preempted
|
* in the middle of a timer callback, then calling del_timer_sync() can
|
* lead to two issues:
|
*
|
* - If the caller is on a remote CPU then it has to spin wait for the timer
|
* handler to complete. This can result in unbound priority inversion.
|
*
|
* - If the caller originates from the task which preempted the timer
|
* handler on the same CPU, then spin waiting for the timer handler to
|
* complete is never going to end.
|
*/
|
void hrtimer_cancel_wait_running(const struct hrtimer *timer)
|
{
|
/* Lockless read. Prevent the compiler from reloading it below */
|
struct hrtimer_clock_base *base = READ_ONCE(timer->base);
|
|
/*
|
* Just relax if the timer expires in hard interrupt context or if
|
* it is currently on the migration base.
|
*/
|
if (!timer->is_soft || is_migration_base(base)) {
|
cpu_relax();
|
return;
|
}
|
|
/*
|
* Mark the base as contended and grab the expiry lock, which is
|
* held by the softirq across the timer callback. Drop the lock
|
* immediately so the softirq can expire the next timer. In theory
|
* the timer could already be running again, but that's more than
|
* unlikely and just causes another wait loop.
|
*/
|
atomic_inc(&base->cpu_base->timer_waiters);
|
spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
|
atomic_dec(&base->cpu_base->timer_waiters);
|
spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
|
}
|
#else
|
static inline void
|
hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
|
static inline void
|
hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
|
static inline void
|
hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
|
static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
|
unsigned long flags) { }
|
#endif
|
|
/**
|
* 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)
|
{
|
int ret;
|
|
do {
|
ret = hrtimer_try_to_cancel(timer);
|
|
if (ret < 0)
|
hrtimer_cancel_wait_running(timer);
|
} while (ret < 0);
|
return ret;
|
}
|
EXPORT_SYMBOL_GPL(hrtimer_cancel);
|
|
/**
|
* hrtimer_get_remaining - get remaining time for the timer
|
* @timer: the timer to read
|
* @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
|
*/
|
ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
|
{
|
unsigned long flags;
|
ktime_t rem;
|
|
lock_hrtimer_base(timer, &flags);
|
if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
|
rem = hrtimer_expires_remaining_adjusted(timer);
|
else
|
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, HRTIMER_ACTIVE_ALL);
|
|
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
|
|
return expires;
|
}
|
|
/**
|
* hrtimer_next_event_without - time until next expiry event w/o one timer
|
* @exclude: timer to exclude
|
*
|
* Returns the next expiry time over all timers except for the @exclude one or
|
* KTIME_MAX if none of them is pending.
|
*/
|
u64 hrtimer_next_event_without(const struct hrtimer *exclude)
|
{
|
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)) {
|
unsigned int active;
|
|
if (!cpu_base->softirq_activated) {
|
active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
|
expires = __hrtimer_next_event_base(cpu_base, exclude,
|
active, KTIME_MAX);
|
}
|
active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
|
expires = __hrtimer_next_event_base(cpu_base, exclude, active,
|
expires);
|
}
|
|
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
|
|
return expires;
|
}
|
#endif
|
|
static inline int hrtimer_clockid_to_base(clockid_t clock_id)
|
{
|
if (likely(clock_id < MAX_CLOCKS)) {
|
int base = hrtimer_clock_to_base_table[clock_id];
|
|
if (likely(base != HRTIMER_MAX_CLOCK_BASES))
|
return base;
|
}
|
WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
|
return HRTIMER_BASE_MONOTONIC;
|
}
|
|
static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
|
enum hrtimer_mode mode)
|
{
|
bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
|
struct hrtimer_cpu_base *cpu_base;
|
int base;
|
|
/*
|
* On PREEMPT_RT enabled kernels hrtimers which are not explicitely
|
* marked for hard interrupt expiry mode are moved into soft
|
* interrupt context for latency reasons and because the callbacks
|
* can invoke functions which might sleep on RT, e.g. spin_lock().
|
*/
|
if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
|
softtimer = true;
|
|
memset(timer, 0, sizeof(struct hrtimer));
|
|
cpu_base = raw_cpu_ptr(&hrtimer_bases);
|
|
/*
|
* POSIX magic: Relative CLOCK_REALTIME timers are not affected by
|
* clock modifications, so they needs to become CLOCK_MONOTONIC to
|
* ensure POSIX compliance.
|
*/
|
if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
|
clock_id = CLOCK_MONOTONIC;
|
|
base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
|
base += hrtimer_clockid_to_base(clock_id);
|
timer->is_soft = softtimer;
|
timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
|
timer->base = &cpu_base->clock_base[base];
|
timerqueue_init(&timer->node);
|
}
|
|
/**
|
* hrtimer_init - initialize a timer to the given clock
|
* @timer: the timer to be initialized
|
* @clock_id: the clock to be used
|
* @mode: The modes which are relevant for intitialization:
|
* HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
|
* HRTIMER_MODE_REL_SOFT
|
*
|
* The PINNED variants of the above can be handed in,
|
* but the PINNED bit is ignored as pinning happens
|
* when the hrtimer is started
|
*/
|
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_clock_base *base;
|
unsigned int seq;
|
|
do {
|
base = READ_ONCE(timer->base);
|
seq = raw_read_seqcount_begin(&base->seq);
|
|
if (timer->state != HRTIMER_STATE_INACTIVE ||
|
base->running == timer)
|
return true;
|
|
} while (read_seqcount_retry(&base->seq, seq) ||
|
base != READ_ONCE(timer->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,
|
unsigned long flags) __must_hold(&cpu_base->lock)
|
{
|
enum hrtimer_restart (*fn)(struct hrtimer *);
|
bool expires_in_hardirq;
|
int restart;
|
|
lockdep_assert_held(&cpu_base->lock);
|
|
debug_deactivate(timer);
|
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 base->running == NULL &&
|
* timer->state == INACTIVE.
|
*/
|
raw_write_seqcount_barrier(&base->seq);
|
|
__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
|
fn = timer->function;
|
|
/*
|
* Clear the 'is relative' flag for the TIME_LOW_RES case. If the
|
* timer is restarted with a period then it becomes an absolute
|
* timer. If its not restarted it does not matter.
|
*/
|
if (IS_ENABLED(CONFIG_TIME_LOW_RES))
|
timer->is_rel = false;
|
|
/*
|
* The timer is marked as running in the CPU base, so it is
|
* protected against migration to a different CPU even if the lock
|
* is dropped.
|
*/
|
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
|
trace_hrtimer_expire_entry(timer, now);
|
expires_in_hardirq = lockdep_hrtimer_enter(timer);
|
|
restart = fn(timer);
|
|
lockdep_hrtimer_exit(expires_in_hardirq);
|
trace_hrtimer_expire_exit(timer);
|
raw_spin_lock_irq(&cpu_base->lock);
|
|
/*
|
* Note: We clear the running state after enqueue_hrtimer and
|
* we do not reprogram 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, HRTIMER_MODE_ABS);
|
|
/*
|
* Separate the ->running assignment from the ->state assignment.
|
*
|
* As with a regular write barrier, this ensures the read side in
|
* hrtimer_active() cannot observe base->running.timer == NULL &&
|
* timer->state == INACTIVE.
|
*/
|
raw_write_seqcount_barrier(&base->seq);
|
|
WARN_ON_ONCE(base->running != timer);
|
base->running = NULL;
|
}
|
|
static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
|
unsigned long flags, unsigned int active_mask)
|
{
|
struct hrtimer_clock_base *base;
|
unsigned int active = cpu_base->active_bases & active_mask;
|
|
for_each_active_base(base, cpu_base, active) {
|
struct timerqueue_node *node;
|
ktime_t basenow;
|
|
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 < hrtimer_get_softexpires_tv64(timer))
|
break;
|
|
__run_hrtimer(cpu_base, base, timer, &basenow, flags);
|
if (active_mask == HRTIMER_ACTIVE_SOFT)
|
hrtimer_sync_wait_running(cpu_base, flags);
|
}
|
}
|
}
|
|
static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
|
{
|
struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
|
unsigned long flags;
|
ktime_t now;
|
|
hrtimer_cpu_base_lock_expiry(cpu_base);
|
raw_spin_lock_irqsave(&cpu_base->lock, flags);
|
|
now = hrtimer_update_base(cpu_base);
|
__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
|
|
cpu_base->softirq_activated = 0;
|
hrtimer_update_softirq_timer(cpu_base, true);
|
|
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
|
hrtimer_cpu_base_unlock_expiry(cpu_base);
|
}
|
|
#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;
|
unsigned long flags;
|
int retries = 0;
|
|
BUG_ON(!cpu_base->hres_active);
|
cpu_base->nr_events++;
|
dev->next_event = KTIME_MAX;
|
|
raw_spin_lock_irqsave(&cpu_base->lock, flags);
|
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 = KTIME_MAX;
|
|
if (!ktime_before(now, cpu_base->softirq_expires_next)) {
|
cpu_base->softirq_expires_next = KTIME_MAX;
|
cpu_base->softirq_activated = 1;
|
raise_softirq_irqoff(HRTIMER_SOFTIRQ);
|
}
|
|
__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
|
|
/* Reevaluate the clock bases for the [soft] next expiry */
|
expires_next = hrtimer_update_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_irqrestore(&cpu_base->lock, flags);
|
|
/* 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_irqsave(&cpu_base->lock, flags);
|
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_irqrestore(&cpu_base->lock, flags);
|
|
delta = ktime_sub(now, entry_time);
|
if ((unsigned int)delta > cpu_base->max_hang_time)
|
cpu_base->max_hang_time = (unsigned int) delta;
|
/*
|
* Limit it to a sensible value as we enforce a longer
|
* delay. Give the CPU at least 100ms to catch up.
|
*/
|
if (delta > 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);
|
pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
|
}
|
|
/* 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);
|
unsigned long flags;
|
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_irqsave(&cpu_base->lock, flags);
|
now = hrtimer_update_base(cpu_base);
|
|
if (!ktime_before(now, cpu_base->softirq_expires_next)) {
|
cpu_base->softirq_expires_next = KTIME_MAX;
|
cpu_base->softirq_activated = 1;
|
raise_softirq_irqoff(HRTIMER_SOFTIRQ);
|
}
|
|
__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
|
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
|
}
|
|
/*
|
* 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;
|
}
|
|
/**
|
* hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
|
* @sl: sleeper to be started
|
* @mode: timer mode abs/rel
|
*
|
* Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
|
* to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
|
*/
|
void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
|
enum hrtimer_mode mode)
|
{
|
/*
|
* Make the enqueue delivery mode check work on RT. If the sleeper
|
* was initialized for hard interrupt delivery, force the mode bit.
|
* This is a special case for hrtimer_sleepers because
|
* hrtimer_init_sleeper() determines the delivery mode on RT so the
|
* fiddling with this decision is avoided at the call sites.
|
*/
|
if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
|
mode |= HRTIMER_MODE_HARD;
|
|
hrtimer_start_expires(&sl->timer, mode);
|
}
|
EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
|
|
static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
|
clockid_t clock_id, enum hrtimer_mode mode)
|
{
|
/*
|
* On PREEMPT_RT enabled kernels hrtimers which are not explicitely
|
* marked for hard interrupt expiry mode are moved into soft
|
* interrupt context either for latency reasons or because the
|
* hrtimer callback takes regular spinlocks or invokes other
|
* functions which are not suitable for hard interrupt context on
|
* PREEMPT_RT.
|
*
|
* The hrtimer_sleeper callback is RT compatible in hard interrupt
|
* context, but there is a latency concern: Untrusted userspace can
|
* spawn many threads which arm timers for the same expiry time on
|
* the same CPU. That causes a latency spike due to the wakeup of
|
* a gazillion threads.
|
*
|
* OTOH, priviledged real-time user space applications rely on the
|
* low latency of hard interrupt wakeups. If the current task is in
|
* a real-time scheduling class, mark the mode for hard interrupt
|
* expiry.
|
*/
|
if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
|
if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
|
mode |= HRTIMER_MODE_HARD;
|
}
|
|
__hrtimer_init(&sl->timer, clock_id, mode);
|
sl->timer.function = hrtimer_wakeup;
|
sl->task = current;
|
}
|
|
/**
|
* hrtimer_init_sleeper - initialize sleeper to the given clock
|
* @sl: sleeper to be initialized
|
* @clock_id: the clock to be used
|
* @mode: timer mode abs/rel
|
*/
|
void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
|
enum hrtimer_mode mode)
|
{
|
debug_init(&sl->timer, clock_id, mode);
|
__hrtimer_init_sleeper(sl, clock_id, mode);
|
|
}
|
EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
|
|
int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
|
{
|
switch(restart->nanosleep.type) {
|
#ifdef CONFIG_COMPAT_32BIT_TIME
|
case TT_COMPAT:
|
if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
|
return -EFAULT;
|
break;
|
#endif
|
case TT_NATIVE:
|
if (put_timespec64(ts, restart->nanosleep.rmtp))
|
return -EFAULT;
|
break;
|
default:
|
BUG();
|
}
|
return -ERESTART_RESTARTBLOCK;
|
}
|
|
static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
|
{
|
struct restart_block *restart;
|
|
do {
|
set_current_state(TASK_INTERRUPTIBLE);
|
hrtimer_sleeper_start_expires(t, 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);
|
|
if (!t->task)
|
return 0;
|
|
restart = ¤t->restart_block;
|
if (restart->nanosleep.type != TT_NONE) {
|
ktime_t rem = hrtimer_expires_remaining(&t->timer);
|
struct timespec64 rmt;
|
|
if (rem <= 0)
|
return 0;
|
rmt = ktime_to_timespec64(rem);
|
|
return nanosleep_copyout(restart, &rmt);
|
}
|
return -ERESTART_RESTARTBLOCK;
|
}
|
|
static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
|
{
|
struct hrtimer_sleeper t;
|
int ret;
|
|
hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
|
HRTIMER_MODE_ABS);
|
hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
|
ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
|
destroy_hrtimer_on_stack(&t.timer);
|
return ret;
|
}
|
|
long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
|
const clockid_t clockid)
|
{
|
struct restart_block *restart;
|
struct hrtimer_sleeper t;
|
int ret = 0;
|
u64 slack;
|
|
slack = current->timer_slack_ns;
|
if (dl_task(current) || rt_task(current))
|
slack = 0;
|
|
hrtimer_init_sleeper_on_stack(&t, clockid, mode);
|
hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
|
ret = do_nanosleep(&t, mode);
|
if (ret != -ERESTART_RESTARTBLOCK)
|
goto out;
|
|
/* Absolute timers do not update the rmtp value and restart: */
|
if (mode == HRTIMER_MODE_ABS) {
|
ret = -ERESTARTNOHAND;
|
goto out;
|
}
|
|
restart = ¤t->restart_block;
|
restart->nanosleep.clockid = t.timer.base->clockid;
|
restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
|
set_restart_fn(restart, hrtimer_nanosleep_restart);
|
out:
|
destroy_hrtimer_on_stack(&t.timer);
|
return ret;
|
}
|
|
#ifdef CONFIG_64BIT
|
|
SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
|
struct __kernel_timespec __user *, rmtp)
|
{
|
struct timespec64 tu;
|
|
if (get_timespec64(&tu, rqtp))
|
return -EFAULT;
|
|
if (!timespec64_valid(&tu))
|
return -EINVAL;
|
|
current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
|
current->restart_block.nanosleep.rmtp = rmtp;
|
return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
|
CLOCK_MONOTONIC);
|
}
|
|
#endif
|
|
#ifdef CONFIG_COMPAT_32BIT_TIME
|
|
SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
|
struct old_timespec32 __user *, rmtp)
|
{
|
struct timespec64 tu;
|
|
if (get_old_timespec32(&tu, rqtp))
|
return -EFAULT;
|
|
if (!timespec64_valid(&tu))
|
return -EINVAL;
|
|
current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
|
current->restart_block.nanosleep.compat_rmtp = rmtp;
|
return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
|
CLOCK_MONOTONIC);
|
}
|
#endif
|
|
#ifdef CONFIG_PREEMPT_RT
|
/*
|
* Sleep for 1 ms in hope whoever holds what we want will let it go.
|
*/
|
void cpu_chill(void)
|
{
|
unsigned int freeze_flag = current->flags & PF_NOFREEZE;
|
struct task_struct *self = current;
|
ktime_t chill_time;
|
|
raw_spin_lock_irq(&self->pi_lock);
|
self->saved_state = self->state;
|
__set_current_state_no_track(TASK_UNINTERRUPTIBLE);
|
raw_spin_unlock_irq(&self->pi_lock);
|
|
chill_time = ktime_set(0, NSEC_PER_MSEC);
|
|
current->flags |= PF_NOFREEZE;
|
schedule_hrtimeout(&chill_time, HRTIMER_MODE_REL_HARD);
|
if (!freeze_flag)
|
current->flags &= ~PF_NOFREEZE;
|
|
raw_spin_lock_irq(&self->pi_lock);
|
__set_current_state_no_track(self->saved_state);
|
self->saved_state = TASK_RUNNING;
|
raw_spin_unlock_irq(&self->pi_lock);
|
}
|
EXPORT_SYMBOL(cpu_chill);
|
#endif
|
|
/*
|
* Functions related to boot-time initialization:
|
*/
|
int hrtimers_prepare_cpu(unsigned int cpu)
|
{
|
struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
|
int i;
|
|
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
|
struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
|
|
clock_b->cpu_base = cpu_base;
|
seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
|
timerqueue_init_head(&clock_b->active);
|
}
|
|
cpu_base->cpu = cpu;
|
cpu_base->active_bases = 0;
|
cpu_base->hres_active = 0;
|
cpu_base->hang_detected = 0;
|
cpu_base->next_timer = NULL;
|
cpu_base->softirq_next_timer = NULL;
|
cpu_base->expires_next = KTIME_MAX;
|
cpu_base->softirq_expires_next = KTIME_MAX;
|
hrtimer_cpu_base_init_expiry_lock(cpu_base);
|
return 0;
|
}
|
|
#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, HRTIMER_MODE_ABS);
|
}
|
}
|
|
int hrtimers_dead_cpu(unsigned int scpu)
|
{
|
struct hrtimer_cpu_base *old_base, *new_base;
|
int i;
|
|
BUG_ON(cpu_online(scpu));
|
tick_cancel_sched_timer(scpu);
|
|
/*
|
* this BH disable ensures that raise_softirq_irqoff() does
|
* not wakeup ksoftirqd (and acquire the pi-lock) while
|
* holding the cpu_base lock
|
*/
|
local_bh_disable();
|
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]);
|
}
|
|
/*
|
* The migration might have changed the first expiring softirq
|
* timer on this CPU. Update it.
|
*/
|
hrtimer_update_softirq_timer(new_base, false);
|
|
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();
|
local_bh_enable();
|
return 0;
|
}
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
void __init hrtimers_init(void)
|
{
|
hrtimers_prepare_cpu(smp_processor_id());
|
open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
|
}
|
|
/**
|
* schedule_hrtimeout_range_clock - sleep until timeout
|
* @expires: timeout value (ktime_t)
|
* @delta: slack in expires timeout (ktime_t)
|
* @mode: timer mode
|
* @clock_id: timer clock to be used
|
*/
|
int __sched
|
schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
|
const enum hrtimer_mode mode, clockid_t clock_id)
|
{
|
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 == 0) {
|
__set_current_state(TASK_RUNNING);
|
return 0;
|
}
|
|
/*
|
* A NULL parameter means "infinite"
|
*/
|
if (!expires) {
|
schedule();
|
return -EINTR;
|
}
|
|
hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
|
hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
|
hrtimer_sleeper_start_expires(&t, 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;
|
}
|
EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
|
|
/**
|
* schedule_hrtimeout_range - sleep until timeout
|
* @expires: timeout value (ktime_t)
|
* @delta: slack in expires timeout (ktime_t)
|
* @mode: timer mode
|
*
|
* 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 unless the current task is explicitly
|
* woken up, (e.g. by wake_up_process()).
|
*
|
* %TASK_INTERRUPTIBLE - the routine may return early if a signal is
|
* delivered to the current task or the current task is explicitly woken
|
* up.
|
*
|
* The current task state is guaranteed to be TASK_RUNNING when this
|
* routine returns.
|
*
|
* Returns 0 when the timer has expired. If the task was woken before the
|
* timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
|
* by an explicit wakeup, it returns -EINTR.
|
*/
|
int __sched schedule_hrtimeout_range(ktime_t *expires, u64 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
|
*
|
* 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 unless the current task is explicitly
|
* woken up, (e.g. by wake_up_process()).
|
*
|
* %TASK_INTERRUPTIBLE - the routine may return early if a signal is
|
* delivered to the current task or the current task is explicitly woken
|
* up.
|
*
|
* The current task state is guaranteed to be TASK_RUNNING when this
|
* routine returns.
|
*
|
* Returns 0 when the timer has expired. If the task was woken before the
|
* timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
|
* by an explicit wakeup, it returns -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);
|
