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/ktime.h>
  10#include <linux/wait.h>
  11#include <linux/string.h>
  12#include <linux/fs.h>
  13#include <linux/sysctl.h>
  14#include <asm/uaccess.h>
  15
  16extern struct ctl_table epoll_table[]; /* for sysctl */
  17/* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
  18   additional memory. */
  19#define MAX_STACK_ALLOC 832
  20#define FRONTEND_STACK_ALLOC    256
  21#define SELECT_STACK_ALLOC      FRONTEND_STACK_ALLOC
  22#define POLL_STACK_ALLOC        FRONTEND_STACK_ALLOC
  23#define WQUEUES_STACK_ALLOC     (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
  24#define N_INLINE_POLL_ENTRIES   (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
  25
  26#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
  27
  28struct poll_table_struct;
  29
  30/* 
  31 * structures and helpers for f_op->poll implementations
  32 */
  33typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
  34
  35/*
  36 * Do not touch the structure directly, use the access functions
  37 * poll_does_not_wait() and poll_requested_events() instead.
  38 */
  39typedef struct poll_table_struct {
  40        poll_queue_proc _qproc;
  41        unsigned long _key;
  42} poll_table;
  43
  44static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
  45{
  46        if (p && p->_qproc && wait_address)
  47                p->_qproc(filp, wait_address, p);
  48}
  49
  50/*
  51 * Return true if it is guaranteed that poll will not wait. This is the case
  52 * if the poll() of another file descriptor in the set got an event, so there
  53 * is no need for waiting.
  54 */
  55static inline bool poll_does_not_wait(const poll_table *p)
  56{
  57        return p == NULL || p->_qproc == NULL;
  58}
  59
  60/*
  61 * Return the set of events that the application wants to poll for.
  62 * This is useful for drivers that need to know whether a DMA transfer has
  63 * to be started implicitly on poll(). You typically only want to do that
  64 * if the application is actually polling for POLLIN and/or POLLOUT.
  65 */
  66static inline unsigned long poll_requested_events(const poll_table *p)
  67{
  68        return p ? p->_key : ~0UL;
  69}
  70
  71static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
  72{
  73        pt->_qproc = qproc;
  74        pt->_key   = ~0UL; /* all events enabled */
  75}
  76
  77struct poll_table_entry {
  78        struct file *filp;
  79        unsigned long key;
  80        wait_queue_t wait;
  81        wait_queue_head_t *wait_address;
  82};
  83
  84/*
  85 * Structures and helpers for select/poll syscall
  86 */
  87struct poll_wqueues {
  88        poll_table pt;
  89        struct poll_table_page *table;
  90        struct task_struct *polling_task;
  91        int triggered;
  92        int error;
  93        int inline_index;
  94        struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
  95};
  96
  97extern void poll_initwait(struct poll_wqueues *pwq);
  98extern void poll_freewait(struct poll_wqueues *pwq);
  99extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
 100                                 ktime_t *expires, unsigned long slack);
 101extern long select_estimate_accuracy(struct timespec *tv);
 102
 103
 104static inline int poll_schedule(struct poll_wqueues *pwq, int state)
 105{
 106        return poll_schedule_timeout(pwq, state, NULL, 0);
 107}
 108
 109/*
 110 * Scalable version of the fd_set.
 111 */
 112
 113typedef struct {
 114        unsigned long *in, *out, *ex;
 115        unsigned long *res_in, *res_out, *res_ex;
 116} fd_set_bits;
 117
 118/*
 119 * How many longwords for "nr" bits?
 120 */
 121#define FDS_BITPERLONG  (8*sizeof(long))
 122#define FDS_LONGS(nr)   (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
 123#define FDS_BYTES(nr)   (FDS_LONGS(nr)*sizeof(long))
 124
 125/*
 126 * We do a VERIFY_WRITE here even though we are only reading this time:
 127 * we'll write to it eventually..
 128 *
 129 * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
 130 */
 131static inline
 132int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 133{
 134        nr = FDS_BYTES(nr);
 135        if (ufdset)
 136                return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
 137
 138        memset(fdset, 0, nr);
 139        return 0;
 140}
 141
 142static inline unsigned long __must_check
 143set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 144{
 145        if (ufdset)
 146                return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
 147        return 0;
 148}
 149
 150static inline
 151void zero_fd_set(unsigned long nr, unsigned long *fdset)
 152{
 153        memset(fdset, 0, FDS_BYTES(nr));
 154}
 155
 156#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
 157
 158extern int do_select(int n, fd_set_bits *fds, struct timespec *end_time);
 159extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
 160                       struct timespec *end_time);
 161extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
 162                           fd_set __user *exp, struct timespec *end_time);
 163
 164extern int poll_select_set_timeout(struct timespec *to, long sec, long nsec);
 165
 166#endif /* KERNEL */
 167
 168#endif /* _LINUX_POLL_H */
 169