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a761a67f59
Resuming timekeeping is a clock-was-set event and uses the clock-was-set notification mechanism. This is in the way of making the clock-was-set update for hrtimers selective so unnecessary IPIs are avoided when a CPU base does not have timers queued which are affected by the clock setting. Distangle it by invoking hrtimer_resume() on each unfreezing CPU and invoke the new timerfd_resume() function from timekeeping_resume() which is the only place where this is needed. Rename hrtimer_resume() to hrtimer_resume_local() to reflect the change. With this the clock_was_set*() functions are not longer required to IPI all CPUs unconditionally and can get some smarts to avoid them. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210713135158.488853478@linutronix.de
539 lines
16 KiB
C
539 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* hrtimers - High-resolution kernel timers
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*
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* Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
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*
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* data type definitions, declarations, prototypes
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*
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* Started by: Thomas Gleixner and Ingo Molnar
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*/
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#ifndef _LINUX_HRTIMER_H
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#define _LINUX_HRTIMER_H
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#include <linux/hrtimer_defs.h>
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#include <linux/rbtree.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/percpu.h>
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#include <linux/seqlock.h>
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#include <linux/timer.h>
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#include <linux/timerqueue.h>
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struct hrtimer_clock_base;
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struct hrtimer_cpu_base;
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/*
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* Mode arguments of xxx_hrtimer functions:
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*
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* HRTIMER_MODE_ABS - Time value is absolute
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* HRTIMER_MODE_REL - Time value is relative to now
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* HRTIMER_MODE_PINNED - Timer is bound to CPU (is only considered
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* when starting the timer)
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* HRTIMER_MODE_SOFT - Timer callback function will be executed in
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* soft irq context
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* HRTIMER_MODE_HARD - Timer callback function will be executed in
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* hard irq context even on PREEMPT_RT.
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*/
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enum hrtimer_mode {
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HRTIMER_MODE_ABS = 0x00,
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HRTIMER_MODE_REL = 0x01,
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HRTIMER_MODE_PINNED = 0x02,
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HRTIMER_MODE_SOFT = 0x04,
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HRTIMER_MODE_HARD = 0x08,
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HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
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HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,
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HRTIMER_MODE_ABS_SOFT = HRTIMER_MODE_ABS | HRTIMER_MODE_SOFT,
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HRTIMER_MODE_REL_SOFT = HRTIMER_MODE_REL | HRTIMER_MODE_SOFT,
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HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT,
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HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT,
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HRTIMER_MODE_ABS_HARD = HRTIMER_MODE_ABS | HRTIMER_MODE_HARD,
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HRTIMER_MODE_REL_HARD = HRTIMER_MODE_REL | HRTIMER_MODE_HARD,
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HRTIMER_MODE_ABS_PINNED_HARD = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_HARD,
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HRTIMER_MODE_REL_PINNED_HARD = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_HARD,
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};
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/*
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* Return values for the callback function
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*/
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enum hrtimer_restart {
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HRTIMER_NORESTART, /* Timer is not restarted */
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HRTIMER_RESTART, /* Timer must be restarted */
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};
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/*
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* Values to track state of the timer
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*
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* Possible states:
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*
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* 0x00 inactive
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* 0x01 enqueued into rbtree
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*
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* The callback state is not part of the timer->state because clearing it would
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* mean touching the timer after the callback, this makes it impossible to free
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* the timer from the callback function.
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*
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* Therefore we track the callback state in:
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*
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* timer->base->cpu_base->running == timer
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*
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* On SMP it is possible to have a "callback function running and enqueued"
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* status. It happens for example when a posix timer expired and the callback
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* queued a signal. Between dropping the lock which protects the posix timer
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* and reacquiring the base lock of the hrtimer, another CPU can deliver the
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* signal and rearm the timer.
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*
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* All state transitions are protected by cpu_base->lock.
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*/
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#define HRTIMER_STATE_INACTIVE 0x00
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#define HRTIMER_STATE_ENQUEUED 0x01
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/**
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* struct hrtimer - the basic hrtimer structure
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* @node: timerqueue node, which also manages node.expires,
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* the absolute expiry time in the hrtimers internal
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* representation. The time is related to the clock on
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* which the timer is based. Is setup by adding
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* slack to the _softexpires value. For non range timers
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* identical to _softexpires.
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* @_softexpires: the absolute earliest expiry time of the hrtimer.
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* The time which was given as expiry time when the timer
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* was armed.
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* @function: timer expiry callback function
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* @base: pointer to the timer base (per cpu and per clock)
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* @state: state information (See bit values above)
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* @is_rel: Set if the timer was armed relative
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* @is_soft: Set if hrtimer will be expired in soft interrupt context.
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* @is_hard: Set if hrtimer will be expired in hard interrupt context
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* even on RT.
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*
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* The hrtimer structure must be initialized by hrtimer_init()
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*/
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struct hrtimer {
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struct timerqueue_node node;
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ktime_t _softexpires;
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enum hrtimer_restart (*function)(struct hrtimer *);
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struct hrtimer_clock_base *base;
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u8 state;
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u8 is_rel;
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u8 is_soft;
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u8 is_hard;
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};
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/**
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* struct hrtimer_sleeper - simple sleeper structure
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* @timer: embedded timer structure
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* @task: task to wake up
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*
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* task is set to NULL, when the timer expires.
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*/
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struct hrtimer_sleeper {
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struct hrtimer timer;
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struct task_struct *task;
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};
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#ifdef CONFIG_64BIT
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# define __hrtimer_clock_base_align ____cacheline_aligned
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#else
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# define __hrtimer_clock_base_align
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#endif
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/**
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* struct hrtimer_clock_base - the timer base for a specific clock
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* @cpu_base: per cpu clock base
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* @index: clock type index for per_cpu support when moving a
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* timer to a base on another cpu.
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* @clockid: clock id for per_cpu support
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* @seq: seqcount around __run_hrtimer
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* @running: pointer to the currently running hrtimer
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* @active: red black tree root node for the active timers
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* @get_time: function to retrieve the current time of the clock
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* @offset: offset of this clock to the monotonic base
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*/
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struct hrtimer_clock_base {
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struct hrtimer_cpu_base *cpu_base;
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unsigned int index;
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clockid_t clockid;
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seqcount_raw_spinlock_t seq;
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struct hrtimer *running;
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struct timerqueue_head active;
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ktime_t (*get_time)(void);
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ktime_t offset;
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} __hrtimer_clock_base_align;
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enum hrtimer_base_type {
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HRTIMER_BASE_MONOTONIC,
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HRTIMER_BASE_REALTIME,
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HRTIMER_BASE_BOOTTIME,
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HRTIMER_BASE_TAI,
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HRTIMER_BASE_MONOTONIC_SOFT,
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HRTIMER_BASE_REALTIME_SOFT,
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HRTIMER_BASE_BOOTTIME_SOFT,
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HRTIMER_BASE_TAI_SOFT,
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HRTIMER_MAX_CLOCK_BASES,
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};
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/**
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* struct hrtimer_cpu_base - the per cpu clock bases
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* @lock: lock protecting the base and associated clock bases
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* and timers
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* @cpu: cpu number
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* @active_bases: Bitfield to mark bases with active timers
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* @clock_was_set_seq: Sequence counter of clock was set events
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* @hres_active: State of high resolution mode
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* @in_hrtirq: hrtimer_interrupt() is currently executing
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* @hang_detected: The last hrtimer interrupt detected a hang
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* @softirq_activated: displays, if the softirq is raised - update of softirq
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* related settings is not required then.
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* @nr_events: Total number of hrtimer interrupt events
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* @nr_retries: Total number of hrtimer interrupt retries
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* @nr_hangs: Total number of hrtimer interrupt hangs
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* @max_hang_time: Maximum time spent in hrtimer_interrupt
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* @softirq_expiry_lock: Lock which is taken while softirq based hrtimer are
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* expired
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* @timer_waiters: A hrtimer_cancel() invocation waits for the timer
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* callback to finish.
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* @expires_next: absolute time of the next event, is required for remote
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* hrtimer enqueue; it is the total first expiry time (hard
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* and soft hrtimer are taken into account)
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* @next_timer: Pointer to the first expiring timer
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* @softirq_expires_next: Time to check, if soft queues needs also to be expired
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* @softirq_next_timer: Pointer to the first expiring softirq based timer
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* @clock_base: array of clock bases for this cpu
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*
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* Note: next_timer is just an optimization for __remove_hrtimer().
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* Do not dereference the pointer because it is not reliable on
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* cross cpu removals.
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*/
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struct hrtimer_cpu_base {
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raw_spinlock_t lock;
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unsigned int cpu;
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unsigned int active_bases;
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unsigned int clock_was_set_seq;
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unsigned int hres_active : 1,
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in_hrtirq : 1,
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hang_detected : 1,
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softirq_activated : 1;
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#ifdef CONFIG_HIGH_RES_TIMERS
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unsigned int nr_events;
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unsigned short nr_retries;
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unsigned short nr_hangs;
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unsigned int max_hang_time;
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#endif
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#ifdef CONFIG_PREEMPT_RT
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spinlock_t softirq_expiry_lock;
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atomic_t timer_waiters;
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#endif
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ktime_t expires_next;
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struct hrtimer *next_timer;
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ktime_t softirq_expires_next;
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struct hrtimer *softirq_next_timer;
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struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
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} ____cacheline_aligned;
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static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
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{
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timer->node.expires = time;
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timer->_softexpires = time;
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}
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static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
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{
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timer->_softexpires = time;
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timer->node.expires = ktime_add_safe(time, delta);
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}
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static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
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{
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timer->_softexpires = time;
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timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
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}
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static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
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{
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timer->node.expires = tv64;
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timer->_softexpires = tv64;
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}
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static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
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{
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timer->node.expires = ktime_add_safe(timer->node.expires, time);
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timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
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}
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static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
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{
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timer->node.expires = ktime_add_ns(timer->node.expires, ns);
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timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
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}
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static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
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{
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return timer->node.expires;
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}
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static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
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{
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return timer->_softexpires;
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}
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static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
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{
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return timer->node.expires;
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}
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static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
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{
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return timer->_softexpires;
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}
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static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
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{
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return ktime_to_ns(timer->node.expires);
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}
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static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
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{
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return ktime_sub(timer->node.expires, timer->base->get_time());
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}
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static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
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{
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return timer->base->get_time();
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}
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static inline int hrtimer_is_hres_active(struct hrtimer *timer)
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{
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return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
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timer->base->cpu_base->hres_active : 0;
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}
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#ifdef CONFIG_HIGH_RES_TIMERS
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struct clock_event_device;
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extern void hrtimer_interrupt(struct clock_event_device *dev);
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extern unsigned int hrtimer_resolution;
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#else
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#define hrtimer_resolution (unsigned int)LOW_RES_NSEC
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#endif
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static inline ktime_t
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__hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
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{
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ktime_t rem = ktime_sub(timer->node.expires, now);
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/*
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* Adjust relative timers for the extra we added in
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* hrtimer_start_range_ns() to prevent short timeouts.
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*/
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if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
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rem -= hrtimer_resolution;
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return rem;
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}
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static inline ktime_t
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hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
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{
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return __hrtimer_expires_remaining_adjusted(timer,
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timer->base->get_time());
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}
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#ifdef CONFIG_TIMERFD
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extern void timerfd_clock_was_set(void);
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extern void timerfd_resume(void);
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#else
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static inline void timerfd_clock_was_set(void) { }
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static inline void timerfd_resume(void) { }
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#endif
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DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
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#ifdef CONFIG_PREEMPT_RT
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void hrtimer_cancel_wait_running(const struct hrtimer *timer);
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#else
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static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
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{
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cpu_relax();
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}
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#endif
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/* Exported timer functions: */
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/* Initialize timers: */
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extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
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enum hrtimer_mode mode);
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extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
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enum hrtimer_mode mode);
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#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
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extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
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enum hrtimer_mode mode);
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extern void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
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clockid_t clock_id,
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enum hrtimer_mode mode);
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extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
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#else
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static inline void hrtimer_init_on_stack(struct hrtimer *timer,
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clockid_t which_clock,
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enum hrtimer_mode mode)
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{
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hrtimer_init(timer, which_clock, mode);
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}
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static inline void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
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clockid_t clock_id,
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enum hrtimer_mode mode)
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{
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hrtimer_init_sleeper(sl, clock_id, mode);
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}
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static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
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#endif
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/* Basic timer operations: */
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extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
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u64 range_ns, const enum hrtimer_mode mode);
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/**
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* hrtimer_start - (re)start an hrtimer
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* @timer: the timer to be added
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* @tim: expiry time
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* @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
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* relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
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* softirq based mode is considered for debug purpose only!
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*/
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static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
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const enum hrtimer_mode mode)
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{
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hrtimer_start_range_ns(timer, tim, 0, mode);
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}
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extern int hrtimer_cancel(struct hrtimer *timer);
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extern int hrtimer_try_to_cancel(struct hrtimer *timer);
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static inline void hrtimer_start_expires(struct hrtimer *timer,
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enum hrtimer_mode mode)
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{
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u64 delta;
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ktime_t soft, hard;
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soft = hrtimer_get_softexpires(timer);
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hard = hrtimer_get_expires(timer);
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delta = ktime_to_ns(ktime_sub(hard, soft));
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hrtimer_start_range_ns(timer, soft, delta, mode);
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}
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void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
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enum hrtimer_mode mode);
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static inline void hrtimer_restart(struct hrtimer *timer)
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{
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hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
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}
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/* Query timers: */
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extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
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/**
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* hrtimer_get_remaining - get remaining time for the timer
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* @timer: the timer to read
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*/
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static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
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{
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return __hrtimer_get_remaining(timer, false);
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}
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extern u64 hrtimer_get_next_event(void);
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extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
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extern bool hrtimer_active(const struct hrtimer *timer);
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/**
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* hrtimer_is_queued - check, whether the timer is on one of the queues
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* @timer: Timer to check
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*
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* Returns: True if the timer is queued, false otherwise
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*
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* The function can be used lockless, but it gives only a current snapshot.
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*/
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static inline bool hrtimer_is_queued(struct hrtimer *timer)
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{
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/* The READ_ONCE pairs with the update functions of timer->state */
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return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
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}
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/*
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* Helper function to check, whether the timer is running the callback
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* function
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*/
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static inline int hrtimer_callback_running(struct hrtimer *timer)
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{
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return timer->base->running == timer;
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}
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/* Forward a hrtimer so it expires after now: */
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extern u64
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hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
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/**
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* hrtimer_forward_now - forward the timer expiry so it expires after now
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* @timer: hrtimer to forward
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* @interval: the interval to forward
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*
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* Forward the timer expiry so it will expire after the current time
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* of the hrtimer clock base. Returns the number of overruns.
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*
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* Can be safely called from the callback function of @timer. If
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* called from other contexts @timer must neither be enqueued nor
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* running the callback and the caller needs to take care of
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* serialization.
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*
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* Note: This only updates the timer expiry value and does not requeue
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* the timer.
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*/
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static inline u64 hrtimer_forward_now(struct hrtimer *timer,
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ktime_t interval)
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{
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return hrtimer_forward(timer, timer->base->get_time(), interval);
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}
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/* Precise sleep: */
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extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
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extern long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
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const clockid_t clockid);
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extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
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const enum hrtimer_mode mode);
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extern int schedule_hrtimeout_range_clock(ktime_t *expires,
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u64 delta,
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const enum hrtimer_mode mode,
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clockid_t clock_id);
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extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
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/* Soft interrupt function to run the hrtimer queues: */
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extern void hrtimer_run_queues(void);
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/* Bootup initialization: */
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extern void __init hrtimers_init(void);
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/* Show pending timers: */
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extern void sysrq_timer_list_show(void);
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int hrtimers_prepare_cpu(unsigned int cpu);
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#ifdef CONFIG_HOTPLUG_CPU
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int hrtimers_dead_cpu(unsigned int cpu);
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#else
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#define hrtimers_dead_cpu NULL
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#endif
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#endif
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