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