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2386 lines
66 KiB
2386 lines
66 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright(C) 2005-2006, Thomas Gleixner <[email protected]> |
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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 |
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* configuration and capabilities. |
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* |
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* Started by: Thomas Gleixner and Ingo Molnar |
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* |
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* Credits: |
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* Based on the original timer wheel code |
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* |
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* Help, testing, suggestions, bugfixes, improvements were |
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* 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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*/ |
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|
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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> |
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|
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#include <linux/uaccess.h> |
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|
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#include <trace/events/timer.h> |
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|
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#include "tick-internal.h" |
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|
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/* |
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* Masks for selecting the soft and hard context timers from |
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* cpu_base->active |
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*/ |
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#define MASK_SHIFT (HRTIMER_BASE_MONOTONIC_SOFT) |
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#define HRTIMER_ACTIVE_HARD ((1U << MASK_SHIFT) - 1) |
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#define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT) |
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#define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD) |
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|
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/* |
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* The timer bases: |
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* |
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* There are more clockids than hrtimer bases. Thus, we index |
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* into the timer bases by the hrtimer_base_type enum. When trying |
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* to reach a base using a clockid, hrtimer_clockid_to_base() |
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* is used to convert from clockid to the proper hrtimer_base_type. |
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*/ |
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DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) = |
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{ |
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.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock), |
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.clock_base = |
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{ |
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{ |
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.index = HRTIMER_BASE_MONOTONIC, |
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.clockid = CLOCK_MONOTONIC, |
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.get_time = &ktime_get, |
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}, |
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{ |
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.index = HRTIMER_BASE_REALTIME, |
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.clockid = CLOCK_REALTIME, |
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.get_time = &ktime_get_real, |
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}, |
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{ |
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.index = HRTIMER_BASE_BOOTTIME, |
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.clockid = CLOCK_BOOTTIME, |
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.get_time = &ktime_get_boottime, |
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}, |
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{ |
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.index = HRTIMER_BASE_TAI, |
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.clockid = CLOCK_TAI, |
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.get_time = &ktime_get_clocktai, |
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}, |
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{ |
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.index = HRTIMER_BASE_MONOTONIC_SOFT, |
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.clockid = CLOCK_MONOTONIC, |
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.get_time = &ktime_get, |
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}, |
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{ |
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.index = HRTIMER_BASE_REALTIME_SOFT, |
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.clockid = CLOCK_REALTIME, |
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.get_time = &ktime_get_real, |
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}, |
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{ |
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.index = HRTIMER_BASE_BOOTTIME_SOFT, |
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.clockid = CLOCK_BOOTTIME, |
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.get_time = &ktime_get_boottime, |
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}, |
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{ |
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.index = HRTIMER_BASE_TAI_SOFT, |
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.clockid = CLOCK_TAI, |
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.get_time = &ktime_get_clocktai, |
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}, |
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} |
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}; |
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|
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static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = { |
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/* Make sure we catch unsupported clockids */ |
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[0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES, |
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|
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[CLOCK_REALTIME] = HRTIMER_BASE_REALTIME, |
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[CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC, |
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[CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME, |
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[CLOCK_TAI] = HRTIMER_BASE_TAI, |
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}; |
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|
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/* |
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* Functions and macros which are different for UP/SMP systems are kept in a |
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* single place |
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*/ |
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#ifdef CONFIG_SMP |
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|
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/* |
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* We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base() |
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* such that hrtimer_callback_running() can unconditionally dereference |
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* timer->base->cpu_base |
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*/ |
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static struct hrtimer_cpu_base migration_cpu_base = { |
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.clock_base = { { |
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.cpu_base = &migration_cpu_base, |
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.seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq, |
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&migration_cpu_base.lock), |
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}, }, |
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}; |
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|
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#define migration_base migration_cpu_base.clock_base[0] |
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|
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static inline bool is_migration_base(struct hrtimer_clock_base *base) |
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{ |
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return base == &migration_base; |
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} |
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|
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/* |
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* We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock |
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* means that all timers which are tied to this base via timer->base are |
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* locked, and the base itself is locked too. |
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* |
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* So __run_timers/migrate_timers can safely modify all timers which could |
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* be found on the lists/queues. |
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* |
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* When the timer's base is locked, and the timer removed from list, it is |
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* possible to set timer->base = &migration_base and drop the lock: the timer |
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* remains locked. |
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*/ |
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static |
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struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, |
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unsigned long *flags) |
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{ |
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struct hrtimer_clock_base *base; |
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|
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for (;;) { |
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base = READ_ONCE(timer->base); |
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if (likely(base != &migration_base)) { |
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raw_spin_lock_irqsave(&base->cpu_base->lock, *flags); |
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if (likely(base == timer->base)) |
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return base; |
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/* The timer has migrated to another CPU: */ |
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raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags); |
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} |
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cpu_relax(); |
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} |
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} |
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|
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/* |
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* We do not migrate the timer when it is expiring before the next |
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* event on the target cpu. When high resolution is enabled, we cannot |
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* reprogram the target cpu hardware and we would cause it to fire |
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* late. To keep it simple, we handle the high resolution enabled and |
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* disabled case similar. |
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* |
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* Called with cpu_base->lock of target cpu held. |
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*/ |
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static int |
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hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base) |
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{ |
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ktime_t expires; |
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|
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expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset); |
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return expires < new_base->cpu_base->expires_next; |
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} |
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|
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static inline |
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struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, |
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int pinned) |
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{ |
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#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) |
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if (static_branch_likely(&timers_migration_enabled) && !pinned) |
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return &per_cpu(hrtimer_bases, get_nohz_timer_target()); |
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#endif |
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return base; |
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} |
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|
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/* |
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* We switch the timer base to a power-optimized selected CPU target, |
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* if: |
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* - NO_HZ_COMMON is enabled |
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* - timer migration is enabled |
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* - the timer callback is not running |
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* - the timer is not the first expiring timer on the new target |
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* |
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* If one of the above requirements is not fulfilled we move the timer |
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* to the current CPU or leave it on the previously assigned CPU if |
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* the timer callback is currently running. |
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*/ |
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static inline struct hrtimer_clock_base * |
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switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, |
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int pinned) |
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{ |
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struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base; |
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struct hrtimer_clock_base *new_base; |
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int basenum = base->index; |
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|
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this_cpu_base = this_cpu_ptr(&hrtimer_bases); |
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new_cpu_base = get_target_base(this_cpu_base, pinned); |
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again: |
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new_base = &new_cpu_base->clock_base[basenum]; |
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|
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if (base != new_base) { |
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/* |
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* We are trying to move timer to new_base. |
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* However we can't change timer's base while it is running, |
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* so we keep it on the same CPU. No hassle vs. reprogramming |
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* the event source in the high resolution case. The softirq |
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* code will take care of this when the timer function has |
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* completed. There is no conflict as we hold the lock until |
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* the timer is enqueued. |
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*/ |
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if (unlikely(hrtimer_callback_running(timer))) |
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return base; |
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|
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/* See the comment in lock_hrtimer_base() */ |
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WRITE_ONCE(timer->base, &migration_base); |
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raw_spin_unlock(&base->cpu_base->lock); |
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raw_spin_lock(&new_base->cpu_base->lock); |
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|
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if (new_cpu_base != this_cpu_base && |
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hrtimer_check_target(timer, new_base)) { |
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raw_spin_unlock(&new_base->cpu_base->lock); |
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raw_spin_lock(&base->cpu_base->lock); |
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new_cpu_base = this_cpu_base; |
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WRITE_ONCE(timer->base, base); |
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goto again; |
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} |
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WRITE_ONCE(timer->base, new_base); |
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} else { |
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if (new_cpu_base != this_cpu_base && |
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hrtimer_check_target(timer, new_base)) { |
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new_cpu_base = this_cpu_base; |
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goto again; |
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} |
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} |
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return new_base; |
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} |
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|
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#else /* CONFIG_SMP */ |
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|
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static inline bool is_migration_base(struct hrtimer_clock_base *base) |
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{ |
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return false; |
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} |
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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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{ |
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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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|
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#endif /* !CONFIG_SMP */ |
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|
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/* |
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* Functions for the union type storage format of ktime_t which are |
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* too large for inlining: |
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*/ |
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#if BITS_PER_LONG < 64 |
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/* |
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* Divide a ktime value by a nanosecond value |
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*/ |
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s64 __ktime_divns(const ktime_t kt, s64 div) |
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{ |
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int sft = 0; |
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s64 dclc; |
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u64 tmp; |
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|
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dclc = ktime_to_ns(kt); |
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tmp = dclc < 0 ? -dclc : dclc; |
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|
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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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} |
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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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/* |
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* Add two ktime values and do a safety check for overflow: |
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*/ |
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ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs) |
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{ |
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ktime_t res = ktime_add_unsafe(lhs, rhs); |
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|
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/* |
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* We use KTIME_SEC_MAX here, the maximum timeout which we can |
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* return to user space in a timespec: |
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*/ |
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if (res < 0 || res < lhs || res < rhs) |
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res = ktime_set(KTIME_SEC_MAX, 0); |
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|
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return res; |
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} |
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EXPORT_SYMBOL_GPL(ktime_add_safe); |
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|
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#ifdef CONFIG_DEBUG_OBJECTS_TIMERS |
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|
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static const struct debug_obj_descr hrtimer_debug_descr; |
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|
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static void *hrtimer_debug_hint(void *addr) |
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{ |
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return ((struct hrtimer *) addr)->function; |
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} |
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|
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/* |
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* fixup_init is called when: |
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* - an active object is initialized |
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*/ |
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static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state) |
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{ |
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struct hrtimer *timer = addr; |
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|
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switch (state) { |
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case ODEBUG_STATE_ACTIVE: |
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hrtimer_cancel(timer); |
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debug_object_init(timer, &hrtimer_debug_descr); |
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return true; |
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default: |
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return false; |
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} |
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} |
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|
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/* |
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* fixup_activate is called when: |
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* - an active object is activated |
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* - an unknown non-static object is activated |
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*/ |
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static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state) |
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{ |
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switch (state) { |
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case ODEBUG_STATE_ACTIVE: |
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WARN_ON(1); |
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fallthrough; |
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default: |
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return false; |
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} |
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} |
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|
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/* |
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* fixup_free is called when: |
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* - an active object is freed |
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*/ |
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static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state) |
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{ |
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struct hrtimer *timer = addr; |
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|
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switch (state) { |
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case ODEBUG_STATE_ACTIVE: |
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hrtimer_cancel(timer); |
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debug_object_free(timer, &hrtimer_debug_descr); |
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return true; |
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default: |
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return false; |
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} |
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} |
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|
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static const struct debug_obj_descr hrtimer_debug_descr = { |
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.name = "hrtimer", |
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.debug_hint = hrtimer_debug_hint, |
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.fixup_init = hrtimer_fixup_init, |
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.fixup_activate = hrtimer_fixup_activate, |
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.fixup_free = hrtimer_fixup_free, |
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}; |
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|
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static inline void debug_hrtimer_init(struct hrtimer *timer) |
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{ |
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debug_object_init(timer, &hrtimer_debug_descr); |
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} |
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|
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static inline void debug_hrtimer_activate(struct hrtimer *timer, |
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enum hrtimer_mode mode) |
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{ |
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debug_object_activate(timer, &hrtimer_debug_descr); |
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} |
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|
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static inline void debug_hrtimer_deactivate(struct hrtimer *timer) |
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{ |
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debug_object_deactivate(timer, &hrtimer_debug_descr); |
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} |
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|
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static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id, |
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enum hrtimer_mode mode); |
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|
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void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id, |
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enum hrtimer_mode mode) |
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{ |
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debug_object_init_on_stack(timer, &hrtimer_debug_descr); |
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__hrtimer_init(timer, clock_id, mode); |
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} |
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EXPORT_SYMBOL_GPL(hrtimer_init_on_stack); |
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|
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static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl, |
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clockid_t clock_id, enum hrtimer_mode mode); |
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|
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void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl, |
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clockid_t clock_id, enum hrtimer_mode mode) |
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{ |
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debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr); |
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__hrtimer_init_sleeper(sl, clock_id, mode); |
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} |
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EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack); |
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|
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void destroy_hrtimer_on_stack(struct hrtimer *timer) |
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{ |
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debug_object_free(timer, &hrtimer_debug_descr); |
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} |
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EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack); |
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|
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#else |
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|
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static inline void debug_hrtimer_init(struct hrtimer *timer) { } |
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static inline void debug_hrtimer_activate(struct hrtimer *timer, |
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enum hrtimer_mode mode) { } |
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static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { } |
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#endif |
|
|
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static inline void |
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debug_init(struct hrtimer *timer, clockid_t clockid, |
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enum hrtimer_mode mode) |
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{ |
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debug_hrtimer_init(timer); |
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trace_hrtimer_init(timer, clockid, mode); |
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} |
|
|
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static inline void debug_activate(struct hrtimer *timer, |
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enum hrtimer_mode mode) |
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{ |
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debug_hrtimer_activate(timer, mode); |
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trace_hrtimer_start(timer, mode); |
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} |
|
|
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static inline void debug_deactivate(struct hrtimer *timer) |
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{ |
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debug_hrtimer_deactivate(timer); |
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trace_hrtimer_cancel(timer); |
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} |
|
|
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static struct hrtimer_clock_base * |
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__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active) |
|
{ |
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unsigned int idx; |
|
|
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if (!*active) |
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return NULL; |
|
|
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idx = __ffs(*active); |
|
*active &= ~(1U << idx); |
|
|
|
return &cpu_base->clock_base[idx]; |
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} |
|
|
|
#define for_each_active_base(base, cpu_base, active) \ |
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while ((base = __next_base((cpu_base), &(active)))) |
|
|
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static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base, |
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const struct hrtimer *exclude, |
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unsigned int active, |
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ktime_t expires_next) |
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{ |
|
struct hrtimer_clock_base *base; |
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ktime_t expires; |
|
|
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for_each_active_base(base, cpu_base, active) { |
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struct timerqueue_node *next; |
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struct hrtimer *timer; |
|
|
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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; |
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else |
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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(). |
|
*/ |
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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. |
|
* |
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* 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 |
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* hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases. |
|
* |
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* 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); |
|
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 |
|
|
|
/* |
|
* 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; |
|
} |
|
|
|
/** |
|
* 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);
|
|
|