include/linux/once_lite.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_ONCE_LITE_H
   3 #define _LINUX_ONCE_LITE_H
   4
   5 #include <linux/types.h>
   6
   7 /* Call a function once. Similar to DO_ONCE(), but does not use jump label
   8  * patching via static keys.
   9  */
  10 #define DO_ONCE_LITE(func, ...)                                         \
  11         DO_ONCE_LITE_IF(true, func, ##__VA_ARGS__)
  12
  13 #define __ONCE_LITE_IF(condition)                                       \
  14         ({                                                              \
  15                 static bool __section(".data.once") __already_done;     \
  16                 bool __ret_cond = !!(condition);                        \
  17                 bool __ret_once = false;                                \
  18                                                                         \
  19                 if (unlikely(__ret_cond && !__already_done)) {          \
  20                         __already_done = true;                          \
  21                         __ret_once = true;                              \
  22                 }                                                       \
  23                 unlikely(__ret_once);                                   \
  24         })
  25
  26 #define DO_ONCE_LITE_IF(condition, func, ...)                           \
  27         ({                                                              \
  28                 bool __ret_do_once = !!(condition);                     \
  29                                                                         \
  30                 if (__ONCE_LITE_IF(__ret_do_once))                      \
  31                         func(__VA_ARGS__);                              \
  32                                                                         \
  33                 unlikely(__ret_do_once);                                \
  34         })
  35
  36 #endif /* _LINUX_ONCE_LITE_H */