LXR linux/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
  24struct poll_table_struct;
  25
  26/* 
  27 * structures and helpers for f_op->poll implementations
  28 */
  29typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
  30
  31typedef struct poll_table_struct {
  32        poll_queue_proc qproc;
  33} poll_table;
  34
  35static 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
  41static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
  42{
  43        pt->qproc = qproc;
  44}
  45
  46struct 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 */
  55struct 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
  63extern void poll_initwait(struct poll_wqueues *pwq);
  64extern void poll_freewait(struct poll_wqueues *pwq);
  65
  66/*
  67 * Scaleable version of the fd_set.
  68 */
  69
  70typedef 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 */
  88static inline
  89int 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
  99static inline unsigned long __must_check
 100set_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
 107static inline
 108void 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
 115extern int do_select(int n, fd_set_bits *fds, s64 *timeout);
 116extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
 117                       s64 *timeout);
 118
 119#endif /* KERNEL */
 120
 121#endif /* _LINUX_POLL_H */
 122