src/common/testpoint/testpoint.hpp

   1 /*
   2  * Copyright (C) 2012 Christian Babeux <christian.babeux@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #ifdef NTESTPOINT
   9
  10 #define testpoint(name)
  11 #define TESTPOINT_DECL(name)
  12
  13 #else /* NTESTPOINT */
  14
  15 #include <urcu.h> /* for caa_likely/unlikely */
  16
  17 extern int lttng_testpoint_activated;
  18
  19 void *lttng_testpoint_lookup(const char *name);
  20
  21 /*
  22  * Testpoint is only active if the global lttng_testpoint_activated flag is
  23  * set.
  24  * Return a non-zero error code to indicate failure.
  25  */
  26 #define testpoint(name) \
  27         ((caa_unlikely(lttng_testpoint_activated)) ? __testpoint_##name##_wrapper() : 0)
  28
  29 /*
  30  * One wrapper per testpoint is generated. This is to keep track of the symbol
  31  * lookup status and the corresponding function pointer, if any.
  32  */
  33 #define _TESTPOINT_DECL(_name)                                                        \
  34         static inline int __testpoint_##_name##_wrapper(void)                         \
  35         {                                                                             \
  36                 int ret = 0;                                                          \
  37                 static int (*tp)(void);                                               \
  38                 static int found;                                                     \
  39                 const char *tp_name = "__testpoint_" #_name;                          \
  40                                                                                       \
  41                 if (tp) {                                                             \
  42                         ret = tp();                                                   \
  43                 } else {                                                              \
  44                         if (!found) {                                                 \
  45                                 tp = (int (*)(void)) lttng_testpoint_lookup(tp_name); \
  46                                 if (tp) {                                             \
  47                                         found = 1;                                    \
  48                                         ret = tp();                                   \
  49                                 } else {                                              \
  50                                         found = -1;                                   \
  51                                 }                                                     \
  52                         }                                                             \
  53                 }                                                                     \
  54                 return ret;                                                           \
  55         }
  56
  57 /* Testpoint declaration */
  58 #define TESTPOINT_DECL(name) _TESTPOINT_DECL(name)
  59
  60 #endif /* NTESTPOINT */