tools/perf/util/trigger.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __TRIGGER_H_
   3 #define __TRIGGER_H_ 1
   4
   5 #include "util/debug.h"
   6 #include "asm/bug.h"
   7
   8 /*
   9  * Use trigger to model operations which need to be executed when
  10  * an event (a signal, for example) is observed.
  11  *
  12  * States and transits:
  13  *
  14  *
  15  *  OFF--> ON --> READY --(hit)--> HIT
  16  *                 ^               |
  17  *                 |            (ready)
  18  *                 |               |
  19  *                  \_____________/
  20  *
  21  * is_hit and is_ready are two key functions to query the state of
  22  * a trigger. is_hit means the event already happen; is_ready means the
  23  * trigger is waiting for the event.
  24  */
  25
  26 struct trigger {
  27         volatile enum {
  28                 TRIGGER_ERROR           = -2,
  29                 TRIGGER_OFF             = -1,
  30                 TRIGGER_ON              = 0,
  31                 TRIGGER_READY           = 1,
  32                 TRIGGER_HIT             = 2,
  33         } state;
  34         const char *name;
  35 };
  36
  37 #define TRIGGER_WARN_ONCE(t, exp) \
  38         WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \
  39                   t->name, t->state, __func__)
  40
  41 static inline bool trigger_is_available(struct trigger *t)
  42 {
  43         return t->state >= 0;
  44 }
  45
  46 static inline bool trigger_is_error(struct trigger *t)
  47 {
  48         return t->state <= TRIGGER_ERROR;
  49 }
  50
  51 static inline void trigger_on(struct trigger *t)
  52 {
  53         TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
  54         t->state = TRIGGER_ON;
  55 }
  56
  57 static inline void trigger_ready(struct trigger *t)
  58 {
  59         if (!trigger_is_available(t))
  60                 return;
  61         t->state = TRIGGER_READY;
  62 }
  63
  64 static inline void trigger_hit(struct trigger *t)
  65 {
  66         if (!trigger_is_available(t))
  67                 return;
  68         TRIGGER_WARN_ONCE(t, TRIGGER_READY);
  69         t->state = TRIGGER_HIT;
  70 }
  71
  72 static inline void trigger_off(struct trigger *t)
  73 {
  74         if (!trigger_is_available(t))
  75                 return;
  76         t->state = TRIGGER_OFF;
  77 }
  78
  79 static inline void trigger_error(struct trigger *t)
  80 {
  81         t->state = TRIGGER_ERROR;
  82 }
  83
  84 static inline bool trigger_is_ready(struct trigger *t)
  85 {
  86         return t->state == TRIGGER_READY;
  87 }
  88
  89 static inline bool trigger_is_hit(struct trigger *t)
  90 {
  91         return t->state == TRIGGER_HIT;
  92 }
  93
  94 #define DEFINE_TRIGGER(n) \
  95 struct trigger n = {.state = TRIGGER_OFF, .name = #n}
  96 #endif