LXR linux/tools/perf/util/trigger.h

   1#ifndef __TRIGGER_H_
   2#define __TRIGGER_H_ 1
   3
   4#include "util/debug.h"
   5#include "asm/bug.h"
   6
   7/*
   8 * Use trigger to model operations which need to be executed when
   9 * an event (a signal, for example) is observed.
  10 *
  11 * States and transits:
  12 *
  13 *
  14 *  OFF--(on)--> READY --(hit)--> HIT
  15 *                 ^               |
  16 *                 |            (ready)
  17 *                 |               |
  18 *                  \_____________/
  19 *
  20 * is_hit and is_ready are two key functions to query the state of
  21 * a trigger. is_hit means the event already happen; is_ready means the
  22 * trigger is waiting for the event.
  23 */
  24
  25struct trigger {
  26        volatile enum {
  27                TRIGGER_ERROR           = -2,
  28                TRIGGER_OFF             = -1,
  29                TRIGGER_READY           = 0,
  30                TRIGGER_HIT             = 1,
  31        } state;
  32        const char *name;
  33};
  34
  35#define TRIGGER_WARN_ONCE(t, exp) \
  36        WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \
  37                  t->name, t->state, __func__)
  38
  39static inline bool trigger_is_available(struct trigger *t)
  40{
  41        return t->state >= 0;
  42}
  43
  44static inline bool trigger_is_error(struct trigger *t)
  45{
  46        return t->state <= TRIGGER_ERROR;
  47}
  48
  49static inline void trigger_on(struct trigger *t)
  50{
  51        TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
  52        t->state = TRIGGER_READY;
  53}
  54
  55static inline void trigger_ready(struct trigger *t)
  56{
  57        if (!trigger_is_available(t))
  58                return;
  59        t->state = TRIGGER_READY;
  60}
  61
  62static inline void trigger_hit(struct trigger *t)
  63{
  64        if (!trigger_is_available(t))
  65                return;
  66        TRIGGER_WARN_ONCE(t, TRIGGER_READY);
  67        t->state = TRIGGER_HIT;
  68}
  69
  70static inline void trigger_off(struct trigger *t)
  71{
  72        if (!trigger_is_available(t))
  73                return;
  74        t->state = TRIGGER_OFF;
  75}
  76
  77static inline void trigger_error(struct trigger *t)
  78{
  79        t->state = TRIGGER_ERROR;
  80}
  81
  82static inline bool trigger_is_ready(struct trigger *t)
  83{
  84        return t->state == TRIGGER_READY;
  85}
  86
  87static inline bool trigger_is_hit(struct trigger *t)
  88{
  89        return t->state == TRIGGER_HIT;
  90}
  91
  92#define DEFINE_TRIGGER(n) \
  93struct trigger n = {.state = TRIGGER_OFF, .name = #n}
  94#endif
  95