eventpoll.h 2.6 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899
  1. /*
  2. * include/linux/eventpoll.h ( Efficent event polling implementation )
  3. * Copyright (C) 2001,...,2003 Davide Libenzi
  4. *
  5. * This program is free software; you can redistribute it and/or modify
  6. * it under the terms of the GNU General Public License as published by
  7. * the Free Software Foundation; either version 2 of the License, or
  8. * (at your option) any later version.
  9. *
  10. * Davide Libenzi <davidel@xmailserver.org>
  11. *
  12. */
  13. #ifndef _LINUX_EVENTPOLL_H
  14. #define _LINUX_EVENTPOLL_H
  15. #include <linux/types.h>
  16. /* Valid opcodes to issue to sys_epoll_ctl() */
  17. #define EPOLL_CTL_ADD 1
  18. #define EPOLL_CTL_DEL 2
  19. #define EPOLL_CTL_MOD 3
  20. /* Set the One Shot behaviour for the target file descriptor */
  21. #define EPOLLONESHOT (1 << 30)
  22. /* Set the Edge Triggered behaviour for the target file descriptor */
  23. #define EPOLLET (1 << 31)
  24. /*
  25. * On x86-64 make the 64bit structure have the same alignment as the
  26. * 32bit structure. This makes 32bit emulation easier.
  27. */
  28. #ifdef __x86_64__
  29. #define EPOLL_PACKED __attribute__((packed))
  30. #else
  31. #define EPOLL_PACKED
  32. #endif
  33. struct epoll_event {
  34. __u32 events;
  35. __u64 data;
  36. } EPOLL_PACKED;
  37. #ifdef __KERNEL__
  38. /* Forward declarations to avoid compiler errors */
  39. struct file;
  40. #ifdef CONFIG_EPOLL
  41. /* Used to initialize the epoll bits inside the "struct file" */
  42. void eventpoll_init_file(struct file *file);
  43. /* Used to release the epoll bits inside the "struct file" */
  44. void eventpoll_release_file(struct file *file);
  45. /*
  46. * This is called from inside fs/file_table.c:__fput() to unlink files
  47. * from the eventpoll interface. We need to have this facility to cleanup
  48. * correctly files that are closed without being removed from the eventpoll
  49. * interface.
  50. */
  51. static inline void eventpoll_release(struct file *file)
  52. {
  53. /*
  54. * Fast check to avoid the get/release of the semaphore. Since
  55. * we're doing this outside the semaphore lock, it might return
  56. * false negatives, but we don't care. It'll help in 99.99% of cases
  57. * to avoid the semaphore lock. False positives simply cannot happen
  58. * because the file in on the way to be removed and nobody ( but
  59. * eventpoll ) has still a reference to this file.
  60. */
  61. if (likely(list_empty(&file->f_ep_links)))
  62. return;
  63. /*
  64. * The file is being closed while it is still linked to an epoll
  65. * descriptor. We need to handle this by correctly unlinking it
  66. * from its containers.
  67. */
  68. eventpoll_release_file(file);
  69. }
  70. #else
  71. static inline void eventpoll_init_file(struct file *file) {}
  72. static inline void eventpoll_release(struct file *file) {}
  73. #endif
  74. #endif /* #ifdef __KERNEL__ */
  75. #endif /* #ifndef _LINUX_EVENTPOLL_H */