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

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