poll.h 4.5 KB

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  1. #ifndef _LINUX_POLL_H
  2. #define _LINUX_POLL_H
  3. #include <asm/poll.h>
  4. #ifdef __KERNEL__
  5. #include <linux/compiler.h>
  6. #include <linux/ktime.h>
  7. #include <linux/wait.h>
  8. #include <linux/string.h>
  9. #include <linux/fs.h>
  10. #include <linux/sysctl.h>
  11. #include <asm/uaccess.h>
  12. extern struct ctl_table epoll_table[]; /* for sysctl */
  13. /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
  14. additional memory. */
  15. #define MAX_STACK_ALLOC 832
  16. #define FRONTEND_STACK_ALLOC 256
  17. #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
  18. #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
  19. #define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
  20. #define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
  21. #define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
  22. struct poll_table_struct;
  23. /*
  24. * structures and helpers for f_op->poll implementations
  25. */
  26. typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
  27. /*
  28. * Do not touch the structure directly, use the access functions
  29. * poll_does_not_wait() and poll_requested_events() instead.
  30. */
  31. typedef struct poll_table_struct {
  32. poll_queue_proc _qproc;
  33. unsigned long _key;
  34. } poll_table;
  35. static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
  36. {
  37. if (p && p->_qproc && wait_address)
  38. p->_qproc(filp, wait_address, p);
  39. }
  40. /*
  41. * Return true if it is guaranteed that poll will not wait. This is the case
  42. * if the poll() of another file descriptor in the set got an event, so there
  43. * is no need for waiting.
  44. */
  45. static inline bool poll_does_not_wait(const poll_table *p)
  46. {
  47. return p == NULL || p->_qproc == NULL;
  48. }
  49. /*
  50. * Return the set of events that the application wants to poll for.
  51. * This is useful for drivers that need to know whether a DMA transfer has
  52. * to be started implicitly on poll(). You typically only want to do that
  53. * if the application is actually polling for POLLIN and/or POLLOUT.
  54. */
  55. static inline unsigned long poll_requested_events(const poll_table *p)
  56. {
  57. return p ? p->_key : ~0UL;
  58. }
  59. static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
  60. {
  61. pt->_qproc = qproc;
  62. pt->_key = ~0UL; /* all events enabled */
  63. }
  64. struct poll_table_entry {
  65. struct file *filp;
  66. unsigned long key;
  67. wait_queue_t wait;
  68. wait_queue_head_t *wait_address;
  69. };
  70. /*
  71. * Structures and helpers for select/poll syscall
  72. */
  73. struct poll_wqueues {
  74. poll_table pt;
  75. struct poll_table_page *table;
  76. struct task_struct *polling_task;
  77. int triggered;
  78. int error;
  79. int inline_index;
  80. struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
  81. };
  82. extern void poll_initwait(struct poll_wqueues *pwq);
  83. extern void poll_freewait(struct poll_wqueues *pwq);
  84. extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
  85. ktime_t *expires, unsigned long slack);
  86. extern long select_estimate_accuracy(struct timespec *tv);
  87. static inline int poll_schedule(struct poll_wqueues *pwq, int state)
  88. {
  89. return poll_schedule_timeout(pwq, state, NULL, 0);
  90. }
  91. /*
  92. * Scalable version of the fd_set.
  93. */
  94. typedef struct {
  95. unsigned long *in, *out, *ex;
  96. unsigned long *res_in, *res_out, *res_ex;
  97. } fd_set_bits;
  98. /*
  99. * How many longwords for "nr" bits?
  100. */
  101. #define FDS_BITPERLONG (8*sizeof(long))
  102. #define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
  103. #define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long))
  104. /*
  105. * We do a VERIFY_WRITE here even though we are only reading this time:
  106. * we'll write to it eventually..
  107. *
  108. * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
  109. */
  110. static inline
  111. int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
  112. {
  113. nr = FDS_BYTES(nr);
  114. if (ufdset)
  115. return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
  116. memset(fdset, 0, nr);
  117. return 0;
  118. }
  119. static inline unsigned long __must_check
  120. set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
  121. {
  122. if (ufdset)
  123. return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
  124. return 0;
  125. }
  126. static inline
  127. void zero_fd_set(unsigned long nr, unsigned long *fdset)
  128. {
  129. memset(fdset, 0, FDS_BYTES(nr));
  130. }
  131. #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
  132. extern int do_select(int n, fd_set_bits *fds, struct timespec *end_time);
  133. extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
  134. struct timespec *end_time);
  135. extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
  136. fd_set __user *exp, struct timespec *end_time);
  137. extern int poll_select_set_timeout(struct timespec *to, long sec, long nsec);
  138. #endif /* KERNEL */
  139. #endif /* _LINUX_POLL_H */