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Diffstat (limited to '')
| -rw-r--r-- | kernel/time/hrtimer.c | 2380 |
1 files changed, 2380 insertions, 0 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c new file mode 100644 index 000000000..5561dabc9 --- /dev/null +++ b/kernel/time/hrtimer.c @@ -0,0 +1,2380 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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, aka timer wheel, + * hrtimers provide finer resolution and accuracy depending on system + * configuration and capabilities. + * + * Started by: Thomas Gleixner and Ingo Molnar + * + * Credits: + * Based on the original timer wheel code + * + * Help, testing, suggestions, bugfixes, improvements were + * provided by: + * + * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel + * et. al. + */ + +#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/interrupt.h> +#include <linux/tick.h> +#include <linux/err.h> +#include <linux/debugobjects.h> +#include <linux/sched/signal.h> +#include <linux/sched/sysctl.h> +#include <linux/sched/rt.h> +#include <linux/sched/deadline.h> +#include <linux/sched/nohz.h> +#include <linux/sched/debug.h> +#include <linux/timer.h> +#include <linux/freezer.h> +#include <linux/compat.h> + +#include <linux/uaccess.h> + +#include <trace/events/timer.h> + +#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) { + /* + * 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() */ + WRITE_ONCE(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; + WRITE_ONCE(timer->base, base); + goto again; + } + WRITE_ONCE(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 bool is_migration_base(struct hrtimer_clock_base *base) +{ + return false; +} + +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, (u32) 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_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) + res = ktime_set(KTIME_SEC_MAX, 0); + + return res; +} + +EXPORT_SYMBOL_GPL(ktime_add_safe); + +#ifdef CONFIG_DEBUG_OBJECTS_TIMERS + +static const 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 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)); +} + +static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base, + struct hrtimer *next_timer, + ktime_t expires_next) +{ + 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 effectively block all timers until the T2 event + * fires. + */ + if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected) + return; + + tick_program_event(expires_next, 1); +} + +/* + * 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; + + __hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next); +} + +/* 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; +} + +static void retrigger_next_event(void *arg); + +/* + * 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) { } + +#endif /* CONFIG_HIGH_RES_TIMERS */ +/* + * Retrigger next event is called after clock was set with interrupts + * disabled through an SMP function call or directly from low level + * resume code. + * + * This is only invoked when: + * - CONFIG_HIGH_RES_TIMERS is enabled. + * - CONFIG_NOHZ_COMMON is enabled + * + * For the other cases this function is empty and because the call sites + * are optimized out it vanishes as well, i.e. no need for lots of + * #ifdeffery. + */ +static void retrigger_next_event(void *arg) +{ + struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases); + + /* + * When high resolution mode or nohz is active, then the offsets of + * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the + * next tick will take care of that. + * + * If high resolution mode is active then the next expiring timer + * must be reevaluated and the clock event device reprogrammed if + * necessary. + * + * In the NOHZ case the update of the offset and the reevaluation + * of the next expiring timer is enough. The return from the SMP + * function call will take care of the reprogramming in case the + * CPU was in a NOHZ idle sleep. + */ + if (!__hrtimer_hres_active(base) && !tick_nohz_active) + return; + + raw_spin_lock(&base->lock); + hrtimer_update_base(base); + if (__hrtimer_hres_active(base)) + hrtimer_force_reprogram(base, 0); + else + hrtimer_update_next_event(base); + raw_spin_unlock(&base->lock); +} + +/* + * 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 (expires >= cpu_base->expires_next) + return; + + /* + * If the hrtimer interrupt is running, then it will reevaluate the + * clock bases and reprogram the clock event device. + */ + if (cpu_base->in_hrtirq) + return; + + cpu_base->next_timer = timer; + + __hrtimer_reprogram(cpu_base, timer, expires); +} + +static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base, + unsigned int active) +{ + struct hrtimer_clock_base *base; + unsigned int seq; + ktime_t expires; + + /* + * Update the base offsets unconditionally so the following + * checks whether the SMP function call is required works. + * + * The update is safe even when the remote CPU is in the hrtimer + * interrupt or the hrtimer soft interrupt and expiring affected + * bases. Either it will see the update before handling a base or + * it will see it when it finishes the processing and reevaluates + * the next expiring timer. + */ + seq = cpu_base->clock_was_set_seq; + hrtimer_update_base(cpu_base); + + /* + * If the sequence did not change over the update then the + * remote CPU already handled it. + */ + if (seq == cpu_base->clock_was_set_seq) + return false; + + /* + * If the remote CPU is currently handling an hrtimer interrupt, it + * will reevaluate the first expiring timer of all clock bases + * before reprogramming. Nothing to do here. + */ + if (cpu_base->in_hrtirq) + return false; + + /* + * Walk the affected clock bases and check whether the first expiring + * timer in a clock base is moving ahead of the first expiring timer of + * @cpu_base. If so, the IPI must be invoked because per CPU clock + * event devices cannot be remotely reprogrammed. + */ + active &= cpu_base->active_bases; + + for_each_active_base(base, cpu_base, active) { + struct timerqueue_node *next; + + next = timerqueue_getnext(&base->active); + expires = ktime_sub(next->expires, base->offset); + if (expires < cpu_base->expires_next) + return true; + + /* Extra check for softirq clock bases */ + if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT) + continue; + if (cpu_base->softirq_activated) + continue; + if (expires < cpu_base->softirq_expires_next) + return true; + } + return false; +} + +/* + * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and + * CLOCK_BOOTTIME (for late sleep time injection). + * + * This requires to update the offsets for these clocks + * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this + * also requires to eventually reprogram the per CPU clock event devices + * when the change moves an affected timer ahead of the first expiring + * timer on that CPU. Obviously remote per CPU clock event devices cannot + * be reprogrammed. The other reason why an IPI has to be sent is when the + * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets + * in the tick, which obviously might be stopped, so this has to bring out + * the remote CPU which might sleep in idle to get this sorted. + */ +void clock_was_set(unsigned int bases) +{ + struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases); + cpumask_var_t mask; + int cpu; + + if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active) + goto out_timerfd; + + if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) { + on_each_cpu(retrigger_next_event, NULL, 1); + goto out_timerfd; + } + + /* Avoid interrupting CPUs if possible */ + cpus_read_lock(); + for_each_online_cpu(cpu) { + unsigned long flags; + + cpu_base = &per_cpu(hrtimer_bases, cpu); + raw_spin_lock_irqsave(&cpu_base->lock, flags); + + if (update_needs_ipi(cpu_base, bases)) + cpumask_set_cpu(cpu, mask); + + raw_spin_unlock_irqrestore(&cpu_base->lock, flags); + } + + preempt_disable(); + smp_call_function_many(mask, retrigger_next_event, NULL, 1); + preempt_enable(); + cpus_read_unlock(); + free_cpumask_var(mask); + +out_timerfd: + timerfd_clock_was_set(); +} + +static void clock_was_set_work(struct work_struct *work) +{ + clock_was_set(CLOCK_SET_WALL); +} + +static DECLARE_WORK(hrtimer_work, clock_was_set_work); + +/* + * Called from timekeeping code to reprogram the hrtimer interrupt device + * on all cpus and to notify timerfd. + */ +void clock_was_set_delayed(void) +{ + schedule_work(&hrtimer_work); +} + +/* + * Called during resume either directly from via timekeeping_resume() + * or in the case of s2idle from tick_unfreeze() to ensure that the + * hrtimers are up to date. + */ +void hrtimers_resume_local(void) +{ + lockdep_assert_irqs_disabled(); + /* Retrigger on the local CPU */ + retrigger_next_event(NULL); +} + +/* + * 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 superfluous 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 reacquire 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 explicitly + * 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 initialization: + * 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 consecutive + * __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 query 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 explicitly + * 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, privileged 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|TASK_FREEZABLE); + hrtimer_sleeper_start_expires(t, mode); + + if (likely(t->task)) + 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.fn = do_no_restart_syscall; + 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.fn = do_no_restart_syscall; + 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 + +/* + * 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_cpu_dying(unsigned int dying_cpu) +{ + struct hrtimer_cpu_base *old_base, *new_base; + int i, ncpu = cpumask_first(cpu_active_mask); + + tick_cancel_sched_timer(dying_cpu); + + old_base = this_cpu_ptr(&hrtimer_bases); + new_base = &per_cpu(hrtimer_bases, ncpu); + + /* + * The caller is globally serialized and nobody else + * takes two locks at once, deadlock is not possible. + */ + raw_spin_lock(&old_base->lock); + raw_spin_lock_nested(&new_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_get_next_event(new_base, HRTIMER_ACTIVE_SOFT); + /* Tell the other CPU to retrigger the next event */ + smp_call_function_single(ncpu, retrigger_next_event, NULL, 0); + + raw_spin_unlock(&new_base->lock); + raw_spin_unlock(&old_base->lock); + + 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); |