include/linux/poll.h

   1 #ifndef _LINUX_POLL_H
   2 #define _LINUX_POLL_H
   3
   4 #include <asm/poll.h>
   5
   6 #ifdef __KERNEL__
   7
   8 #include <linux/compiler.h>
   9 #include <linux/wait.h>
  10 #include <linux/string.h>
  11 #include <linux/fs.h>
  12 #include <linux/sched.h>
  13 #include <asm/uaccess.h>
  14
  15 /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
  16    additional memory. */
  17 #define MAX_STACK_ALLOC 832
  18 #define FRONTEND_STACK_ALLOC    256
  19 #define SELECT_STACK_ALLOC      FRONTEND_STACK_ALLOC
  20 #define POLL_STACK_ALLOC        FRONTEND_STACK_ALLOC
  21 #define WQUEUES_STACK_ALLOC     (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
  22 #define N_INLINE_POLL_ENTRIES   (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
  23
  24 struct poll_table_struct;
  25
  26 /*
  27  * structures and helpers for f_op->poll implementations
  28  */
  29 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
  30
  31 typedef struct poll_table_struct {
  32         poll_queue_proc qproc;
  33 } poll_table;
  34
  35 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
  36 {
  37         if (p && wait_address)
  38                 p->qproc(filp, wait_address, p);
  39 }
  40
  41 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
  42 {
  43         pt->qproc = qproc;
  44 }
  45
  46 struct poll_table_entry {
  47         struct file * filp;
  48         wait_queue_t wait;
  49         wait_queue_head_t * wait_address;
  50 };
  51
  52 /*
  53  * Structures and helpers for sys_poll/sys_poll
  54  */
  55 struct poll_wqueues {
  56         poll_table pt;
  57         struct poll_table_page * table;
  58         int error;
  59         int inline_index;
  60         struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
  61 };
  62
  63 extern void poll_initwait(struct poll_wqueues *pwq);
  64 extern void poll_freewait(struct poll_wqueues *pwq);
  65
  66 /*
  67  * Scaleable version of the fd_set.
  68  */
  69
  70 typedef struct {
  71         unsigned long *in, *out, *ex;
  72         unsigned long *res_in, *res_out, *res_ex;
  73 } fd_set_bits;
  74
  75 /*
  76  * How many longwords for "nr" bits?
  77  */
  78 #define FDS_BITPERLONG  (8*sizeof(long))
  79 #define FDS_LONGS(nr)   (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
  80 #define FDS_BYTES(nr)   (FDS_LONGS(nr)*sizeof(long))
  81
  82 /*
  83  * We do a VERIFY_WRITE here even though we are only reading this time:
  84  * we'll write to it eventually..
  85  *
  86  * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
  87  */
  88 static inline
  89 int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
  90 {
  91         nr = FDS_BYTES(nr);
  92         if (ufdset)
  93                 return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
  94
  95         memset(fdset, 0, nr);
  96         return 0;
  97 }
  98
  99 static inline unsigned long __must_check
 100 set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 101 {
 102         if (ufdset)
 103                 return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
 104         return 0;
 105 }
 106
 107 static inline
 108 void zero_fd_set(unsigned long nr, unsigned long *fdset)
 109 {
 110         memset(fdset, 0, FDS_BYTES(nr));
 111 }
 112
 113 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
 114
 115 extern int do_select(int n, fd_set_bits *fds, s64 *timeout);
 116 extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
 117                        s64 *timeout);
 118
 119 #endif /* KERNEL */
 120
 121 #endif /* _LINUX_POLL_H */