LXR linux/include/linux/timer.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_TIMER_H
   3#define _LINUX_TIMER_H
   4
   5#include <linux/list.h>
   6#include <linux/ktime.h>
   7#include <linux/stddef.h>
   8#include <linux/debugobjects.h>
   9#include <linux/stringify.h>
  10
  11struct timer_list {
  12        /*
  13         * All fields that change during normal runtime grouped to the
  14         * same cacheline
  15         */
  16        struct hlist_node       entry;
  17        unsigned long           expires;
  18        void                    (*function)(struct timer_list *);
  19        u32                     flags;
  20
  21#ifdef CONFIG_LOCKDEP
  22        struct lockdep_map      lockdep_map;
  23#endif
  24};
  25
  26#ifdef CONFIG_LOCKDEP
  27/*
  28 * NB: because we have to copy the lockdep_map, setting the lockdep_map key
  29 * (second argument) here is required, otherwise it could be initialised to
  30 * the copy of the lockdep_map later! We use the pointer to and the string
  31 * "<file>:<line>" as the key resp. the name of the lockdep_map.
  32 */
  33#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn)                            \
  34        .lockdep_map = STATIC_LOCKDEP_MAP_INIT(_kn, &_kn),
  35#else
  36#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn)
  37#endif
  38
  39/**
  40 * @TIMER_DEFERRABLE: A deferrable timer will work normally when the
  41 * system is busy, but will not cause a CPU to come out of idle just
  42 * to service it; instead, the timer will be serviced when the CPU
  43 * eventually wakes up with a subsequent non-deferrable timer.
  44 *
  45 * @TIMER_IRQSAFE: An irqsafe timer is executed with IRQ disabled and
  46 * it's safe to wait for the completion of the running instance from
  47 * IRQ handlers, for example, by calling del_timer_sync().
  48 *
  49 * Note: The irq disabled callback execution is a special case for
  50 * workqueue locking issues. It's not meant for executing random crap
  51 * with interrupts disabled. Abuse is monitored!
  52 *
  53 * @TIMER_PINNED: A pinned timer will not be affected by any timer
  54 * placement heuristics (like, NOHZ) and will always expire on the CPU
  55 * on which the timer was enqueued.
  56 *
  57 * Note: Because enqueuing of timers can migrate the timer from one
  58 * CPU to another, pinned timers are not guaranteed to stay on the
  59 * initialy selected CPU.  They move to the CPU on which the enqueue
  60 * function is invoked via mod_timer() or add_timer().  If the timer
  61 * should be placed on a particular CPU, then add_timer_on() has to be
  62 * used.
  63 */
  64#define TIMER_CPUMASK           0x0003FFFF
  65#define TIMER_MIGRATING         0x00040000
  66#define TIMER_BASEMASK          (TIMER_CPUMASK | TIMER_MIGRATING)
  67#define TIMER_DEFERRABLE        0x00080000
  68#define TIMER_PINNED            0x00100000
  69#define TIMER_IRQSAFE           0x00200000
  70#define TIMER_INIT_FLAGS        (TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE)
  71#define TIMER_ARRAYSHIFT        22
  72#define TIMER_ARRAYMASK         0xFFC00000
  73
  74#define TIMER_TRACE_FLAGMASK    (TIMER_MIGRATING | TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE)
  75
  76#define __TIMER_INITIALIZER(_function, _flags) {                \
  77                .entry = { .next = TIMER_ENTRY_STATIC },        \
  78                .function = (_function),                        \
  79                .flags = (_flags),                              \
  80                __TIMER_LOCKDEP_MAP_INITIALIZER(                \
  81                        __FILE__ ":" __stringify(__LINE__))     \
  82        }
  83
  84#define DEFINE_TIMER(_name, _function)                          \
  85        struct timer_list _name =                               \
  86                __TIMER_INITIALIZER(_function, 0)
  87
  88/*
  89 * LOCKDEP and DEBUG timer interfaces.
  90 */
  91void init_timer_key(struct timer_list *timer,
  92                    void (*func)(struct timer_list *), unsigned int flags,
  93                    const char *name, struct lock_class_key *key);
  94
  95#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
  96extern void init_timer_on_stack_key(struct timer_list *timer,
  97                                    void (*func)(struct timer_list *),
  98                                    unsigned int flags, const char *name,
  99                                    struct lock_class_key *key);
 100#else
 101static inline void init_timer_on_stack_key(struct timer_list *timer,
 102                                           void (*func)(struct timer_list *),
 103                                           unsigned int flags,
 104                                           const char *name,
 105                                           struct lock_class_key *key)
 106{
 107        init_timer_key(timer, func, flags, name, key);
 108}
 109#endif
 110
 111#ifdef CONFIG_LOCKDEP
 112#define __init_timer(_timer, _fn, _flags)                               \
 113        do {                                                            \
 114                static struct lock_class_key __key;                     \
 115                init_timer_key((_timer), (_fn), (_flags), #_timer, &__key);\
 116        } while (0)
 117
 118#define __init_timer_on_stack(_timer, _fn, _flags)                      \
 119        do {                                                            \
 120                static struct lock_class_key __key;                     \
 121                init_timer_on_stack_key((_timer), (_fn), (_flags),      \
 122                                        #_timer, &__key);                \
 123        } while (0)
 124#else
 125#define __init_timer(_timer, _fn, _flags)                               \
 126        init_timer_key((_timer), (_fn), (_flags), NULL, NULL)
 127#define __init_timer_on_stack(_timer, _fn, _flags)                      \
 128        init_timer_on_stack_key((_timer), (_fn), (_flags), NULL, NULL)
 129#endif
 130
 131/**
 132 * timer_setup - prepare a timer for first use
 133 * @timer: the timer in question
 134 * @callback: the function to call when timer expires
 135 * @flags: any TIMER_* flags
 136 *
 137 * Regular timer initialization should use either DEFINE_TIMER() above,
 138 * or timer_setup(). For timers on the stack, timer_setup_on_stack() must
 139 * be used and must be balanced with a call to destroy_timer_on_stack().
 140 */
 141#define timer_setup(timer, callback, flags)                     \
 142        __init_timer((timer), (callback), (flags))
 143
 144#define timer_setup_on_stack(timer, callback, flags)            \
 145        __init_timer_on_stack((timer), (callback), (flags))
 146
 147#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 148extern void destroy_timer_on_stack(struct timer_list *timer);
 149#else
 150static inline void destroy_timer_on_stack(struct timer_list *timer) { }
 151#endif
 152
 153#define from_timer(var, callback_timer, timer_fieldname) \
 154        container_of(callback_timer, typeof(*var), timer_fieldname)
 155
 156/**
 157 * timer_pending - is a timer pending?
 158 * @timer: the timer in question
 159 *
 160 * timer_pending will tell whether a given timer is currently pending,
 161 * or not. Callers must ensure serialization wrt. other operations done
 162 * to this timer, eg. interrupt contexts, or other CPUs on SMP.
 163 *
 164 * return value: 1 if the timer is pending, 0 if not.
 165 */
 166static inline int timer_pending(const struct timer_list * timer)
 167{
 168        return !hlist_unhashed_lockless(&timer->entry);
 169}
 170
 171extern void add_timer_on(struct timer_list *timer, int cpu);
 172extern int del_timer(struct timer_list * timer);
 173extern int mod_timer(struct timer_list *timer, unsigned long expires);
 174extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
 175extern int timer_reduce(struct timer_list *timer, unsigned long expires);
 176
 177/*
 178 * The jiffies value which is added to now, when there is no timer
 179 * in the timer wheel:
 180 */
 181#define NEXT_TIMER_MAX_DELTA    ((1UL << 30) - 1)
 182
 183extern void add_timer(struct timer_list *timer);
 184
 185extern int try_to_del_timer_sync(struct timer_list *timer);
 186
 187#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
 188  extern int del_timer_sync(struct timer_list *timer);
 189#else
 190# define del_timer_sync(t)              del_timer(t)
 191#endif
 192
 193#define del_singleshot_timer_sync(t) del_timer_sync(t)
 194
 195extern void init_timers(void);
 196struct hrtimer;
 197extern enum hrtimer_restart it_real_fn(struct hrtimer *);
 198
 199#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
 200struct ctl_table;
 201
 202extern unsigned int sysctl_timer_migration;
 203int timer_migration_handler(struct ctl_table *table, int write,
 204                            void *buffer, size_t *lenp, loff_t *ppos);
 205#endif
 206
 207unsigned long __round_jiffies(unsigned long j, int cpu);
 208unsigned long __round_jiffies_relative(unsigned long j, int cpu);
 209unsigned long round_jiffies(unsigned long j);
 210unsigned long round_jiffies_relative(unsigned long j);
 211
 212unsigned long __round_jiffies_up(unsigned long j, int cpu);
 213unsigned long __round_jiffies_up_relative(unsigned long j, int cpu);
 214unsigned long round_jiffies_up(unsigned long j);
 215unsigned long round_jiffies_up_relative(unsigned long j);
 216
 217#ifdef CONFIG_HOTPLUG_CPU
 218int timers_prepare_cpu(unsigned int cpu);
 219int timers_dead_cpu(unsigned int cpu);
 220#else
 221#define timers_prepare_cpu      NULL
 222#define timers_dead_cpu         NULL
 223#endif
 224
 225#endif
 226