eventpoll.h 2.9 KB

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  1. /*
  2. * include/linux/eventpoll.h ( Efficent event polling implementation )
  3. * Copyright (C) 2001,...,2006 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. * UML/x86_64 needs the same packing as x86_64 - UML + UML_X86 +
  29. * 64_BIT adds up to UML/x86_64.
  30. */
  31. #ifdef __x86_64__
  32. #define EPOLL_PACKED __attribute__((packed))
  33. #else
  34. #if defined(CONFIG_UML) && defined(CONFIG_UML_X86) && defined(CONFIG_64BIT)
  35. #define EPOLL_PACKED __attribute__((packed))
  36. #else
  37. #define EPOLL_PACKED
  38. #endif
  39. #endif
  40. struct epoll_event {
  41. __u32 events;
  42. __u64 data;
  43. } EPOLL_PACKED;
  44. #ifdef __KERNEL__
  45. /* Forward declarations to avoid compiler errors */
  46. struct file;
  47. #ifdef CONFIG_EPOLL
  48. /* Used to initialize the epoll bits inside the "struct file" */
  49. static inline void eventpoll_init_file(struct file *file)
  50. {
  51. INIT_LIST_HEAD(&file->f_ep_links);
  52. spin_lock_init(&file->f_ep_lock);
  53. }
  54. /* Used to release the epoll bits inside the "struct file" */
  55. void eventpoll_release_file(struct file *file);
  56. /*
  57. * This is called from inside fs/file_table.c:__fput() to unlink files
  58. * from the eventpoll interface. We need to have this facility to cleanup
  59. * correctly files that are closed without being removed from the eventpoll
  60. * interface.
  61. */
  62. static inline void eventpoll_release(struct file *file)
  63. {
  64. /*
  65. * Fast check to avoid the get/release of the semaphore. Since
  66. * we're doing this outside the semaphore lock, it might return
  67. * false negatives, but we don't care. It'll help in 99.99% of cases
  68. * to avoid the semaphore lock. False positives simply cannot happen
  69. * because the file in on the way to be removed and nobody ( but
  70. * eventpoll ) has still a reference to this file.
  71. */
  72. if (likely(list_empty(&file->f_ep_links)))
  73. return;
  74. /*
  75. * The file is being closed while it is still linked to an epoll
  76. * descriptor. We need to handle this by correctly unlinking it
  77. * from its containers.
  78. */
  79. eventpoll_release_file(file);
  80. }
  81. #else
  82. static inline void eventpoll_init_file(struct file *file) {}
  83. static inline void eventpoll_release(struct file *file) {}
  84. #endif
  85. #endif /* #ifdef __KERNEL__ */
  86. #endif /* #ifndef _LINUX_EVENTPOLL_H */