root/include/linux/timer.h

INCLUDED FROM

DEFINITIONS

1. init_timer_on_stack_key
2. destroy_timer_on_stack
3. timer_pending

   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 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  */
  90 void 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
  95 extern 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
 100 static 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
 147 extern void destroy_timer_on_stack(struct timer_list *timer);
 148 #else
 149 static 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  */
 165 static inline int timer_pending(const struct timer_list * timer)
 166 {
 167         return timer->entry.pprev != NULL;
 168 }
 169 
 170 extern void add_timer_on(struct timer_list *timer, int cpu);
 171 extern int del_timer(struct timer_list * timer);
 172 extern int mod_timer(struct timer_list *timer, unsigned long expires);
 173 extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
 174 extern 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 
 182 extern void add_timer(struct timer_list *timer);
 183 
 184 extern int try_to_del_timer_sync(struct timer_list *timer);
 185 
 186 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
 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 
 194 extern void init_timers(void);
 195 extern void run_local_timers(void);
 196 struct hrtimer;
 197 extern enum hrtimer_restart it_real_fn(struct hrtimer *);
 198 
 199 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
 200 struct ctl_table;
 201 
 202 extern unsigned int sysctl_timer_migration;
 203 int timer_migration_handler(struct ctl_table *table, int write,
 204                             void __user *buffer, size_t *lenp,
 205                             loff_t *ppos);
 206 #endif
 207 
 208 unsigned long __round_jiffies(unsigned long j, int cpu);
 209 unsigned long __round_jiffies_relative(unsigned long j, int cpu);
 210 unsigned long round_jiffies(unsigned long j);
 211 unsigned long round_jiffies_relative(unsigned long j);
 212 
 213 unsigned long __round_jiffies_up(unsigned long j, int cpu);
 214 unsigned long __round_jiffies_up_relative(unsigned long j, int cpu);
 215 unsigned long round_jiffies_up(unsigned long j);
 216 unsigned long round_jiffies_up_relative(unsigned long j);
 217 
 218 #ifdef CONFIG_HOTPLUG_CPU
 219 int timers_prepare_cpu(unsigned int cpu);
 220 int 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