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_ARRAYSHIFT        22
  71#define TIMER_ARRAYMASK         0xFFC00000
  72
  73#define TIMER_TRACE_FLAGMASK    (TIMER_MIGRATING | TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE)
  74
  75#define __TIMER_INITIALIZER(_function, _flags) {                \
  76                .entry = { .next = TIMER_ENTRY_STATIC },        \
  77                .function = (_function),                        \
  78                .flags = (_flags),                              \
  79                __TIMER_LOCKDEP_MAP_INITIALIZER(                \
  80                        __FILE__ ":" __stringify(__LINE__))     \
  81        }
  82
  83#define DEFINE_TIMER(_name, _function)                          \
  84        struct timer_list _name =                               \
  85                __TIMER_INITIALIZER(_function, 0)
  86
  87/*
  88 * LOCKDEP and DEBUG timer interfaces.
  89 */
  90void init_timer_key(struct timer_list *timer,
  91                    void (*func)(struct timer_list *), unsigned int flags,
  92                    const char *name, struct lock_class_key *key);
  93
  94#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
  95extern void init_timer_on_stack_key(struct timer_list *timer,
  96                                    void (*func)(struct timer_list *),
  97                                    unsigned int flags, const char *name,
  98                                    struct lock_class_key *key);
  99#else
 100static inline void init_timer_on_stack_key(struct timer_list *timer,
 101                                           void (*func)(struct timer_list *),
 102                                           unsigned int flags,
 103                                           const char *name,
 104                                           struct lock_class_key *key)
 105{
 106        init_timer_key(timer, func, flags, name, key);
 107}
 108#endif
 109
 110#ifdef CONFIG_LOCKDEP
 111#define __init_timer(_timer, _fn, _flags)                               \
 112        do {                                                            \
 113                static struct lock_class_key __key;                     \
 114                init_timer_key((_timer), (_fn), (_flags), #_timer, &__key);\
 115        } while (0)
 116
 117#define __init_timer_on_stack(_timer, _fn, _flags)                      \
 118        do {                                                            \
 119                static struct lock_class_key __key;                     \
 120                init_timer_on_stack_key((_timer), (_fn), (_flags),      \
 121                                        #_timer, &__key);                \
 122        } while (0)
 123#else
 124#define __init_timer(_timer, _fn, _flags)                               \
 125        init_timer_key((_timer), (_fn), (_flags), NULL, NULL)
 126#define __init_timer_on_stack(_timer, _fn, _flags)                      \
 127        init_timer_on_stack_key((_timer), (_fn), (_flags), NULL, NULL)
 128#endif
 129
 130/**
 131 * timer_setup - prepare a timer for first use
 132 * @timer: the timer in question
 133 * @callback: the function to call when timer expires
 134 * @flags: any TIMER_* flags
 135 *
 136 * Regular timer initialization should use either DEFINE_TIMER() above,
 137 * or timer_setup(). For timers on the stack, timer_setup_on_stack() must
 138 * be used and must be balanced with a call to destroy_timer_on_stack().
 139 */
 140#define timer_setup(timer, callback, flags)                     \
 141        __init_timer((timer), (callback), (flags))
 142
 143#define timer_setup_on_stack(timer, callback, flags)            \
 144        __init_timer_on_stack((timer), (callback), (flags))
 145
 146#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 147extern void destroy_timer_on_stack(struct timer_list *timer);
 148#else
 149static inline void destroy_timer_on_stack(struct timer_list *timer) { }
 150#endif
 151
 152#define from_timer(var, callback_timer, timer_fieldname) \
 153        container_of(callback_timer, typeof(*var), timer_fieldname)
 154
 155/**
 156 * timer_pending - is a timer pending?
 157 * @timer: the timer in question
 158 *
 159 * timer_pending will tell whether a given timer is currently pending,
 160 * or not. Callers must ensure serialization wrt. other operations done
 161 * to this timer, eg. interrupt contexts, or other CPUs on SMP.
 162 *
 163 * return value: 1 if the timer is pending, 0 if not.
 164 */
 165static inline int timer_pending(const struct timer_list * timer)
 166{
 167        return timer->entry.pprev != NULL;
 168}
 169
 170extern void add_timer_on(struct timer_list *timer, int cpu);
 171extern int del_timer(struct timer_list * timer);
 172extern int mod_timer(struct timer_list *timer, unsigned long expires);
 173extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
 174extern int timer_reduce(struct timer_list *timer, unsigned long expires);
 175
 176/*
 177 * The jiffies value which is added to now, when there is no timer
 178 * in the timer wheel:
 179 */
 180#define NEXT_TIMER_MAX_DELTA    ((1UL << 30) - 1)
 181
 182extern void add_timer(struct timer_list *timer);
 183
 184extern int try_to_del_timer_sync(struct timer_list *timer);
 185
 186#ifdef CONFIG_SMP
 187  extern int del_timer_sync(struct timer_list *timer);
 188#else
 189# define del_timer_sync(t)              del_timer(t)
 190#endif
 191
 192#define del_singleshot_timer_sync(t) del_timer_sync(t)
 193
 194extern void init_timers(void);
 195extern void run_local_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 __user *buffer, size_t *lenp,
 205                            loff_t *ppos);
 206#endif
 207
 208unsigned long __round_jiffies(unsigned long j, int cpu);
 209unsigned long __round_jiffies_relative(unsigned long j, int cpu);
 210unsigned long round_jiffies(unsigned long j);
 211unsigned long round_jiffies_relative(unsigned long j);
 212
 213unsigned long __round_jiffies_up(unsigned long j, int cpu);
 214unsigned long __round_jiffies_up_relative(unsigned long j, int cpu);
 215unsigned long round_jiffies_up(unsigned long j);
 216unsigned long round_jiffies_up_relative(unsigned long j);
 217
 218#ifdef CONFIG_HOTPLUG_CPU
 219int timers_prepare_cpu(unsigned int cpu);
 220int timers_dead_cpu(unsigned int cpu);
 221#else
 222#define timers_prepare_cpu      NULL
 223#define timers_dead_cpu         NULL
 224#endif
 225
 226#endif
 227