tools/perf/util/trigger.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __TRIGGER_H_
   3 #define __TRIGGER_H_ 1
   4
   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
  25 struct trigger {
  26         volatile enum {
  27                 TRIGGER_ERROR           = -2,
  28                 TRIGGER_OFF             = -1,
  29                 TRIGGER_ON              = 0,
  30                 TRIGGER_READY           = 1,
  31                 TRIGGER_HIT             = 2,
  32         } state;
  33         const char *name;
  34 };
  35
  36 #define TRIGGER_WARN_ONCE(t, exp) \
  37         WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \
  38                   t->name, t->state, __func__)
  39
  40 static inline bool trigger_is_available(struct trigger *t)
  41 {
  42         return t->state >= 0;
  43 }
  44
  45 static inline bool trigger_is_error(struct trigger *t)
  46 {
  47         return t->state <= TRIGGER_ERROR;
  48 }
  49
  50 static inline void trigger_on(struct trigger *t)
  51 {
  52         TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
  53         t->state = TRIGGER_ON;
  54 }
  55
  56 static inline void trigger_ready(struct trigger *t)
  57 {
  58         if (!trigger_is_available(t))
  59                 return;
  60         t->state = TRIGGER_READY;
  61 }
  62
  63 static inline void trigger_hit(struct trigger *t)
  64 {
  65         if (!trigger_is_available(t))
  66                 return;
  67         TRIGGER_WARN_ONCE(t, TRIGGER_READY);
  68         t->state = TRIGGER_HIT;
  69 }
  70
  71 static inline void trigger_off(struct trigger *t)
  72 {
  73         if (!trigger_is_available(t))
  74                 return;
  75         t->state = TRIGGER_OFF;
  76 }
  77
  78 static inline void trigger_error(struct trigger *t)
  79 {
  80         t->state = TRIGGER_ERROR;
  81 }
  82
  83 static inline bool trigger_is_ready(struct trigger *t)
  84 {
  85         return t->state == TRIGGER_READY;
  86 }
  87
  88 static inline bool trigger_is_hit(struct trigger *t)
  89 {
  90         return t->state == TRIGGER_HIT;
  91 }
  92
  93 #define DEFINE_TRIGGER(n) \
  94 struct trigger n = {.state = TRIGGER_OFF, .name = #n}
  95 #endif