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 #define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
  25
  26 struct poll_table_struct;
  27
  28 /*
  29  * structures and helpers for f_op->poll implementations
  30  */
  31 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
  32
  33 typedef struct poll_table_struct {
  34         poll_queue_proc qproc;
  35 } poll_table;
  36
  37 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
  38 {
  39         if (p && wait_address)
  40                 p->qproc(filp, wait_address, p);
  41 }
  42
  43 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
  44 {
  45         pt->qproc = qproc;
  46 }
  47
  48 struct poll_table_entry {
  49         struct file * filp;
  50         wait_queue_t wait;
  51         wait_queue_head_t * wait_address;
  52 };
  53
  54 /*
  55  * Structures and helpers for sys_poll/sys_poll
  56  */
  57 struct poll_wqueues {
  58         poll_table pt;
  59         struct poll_table_page * table;
  60         int error;
  61         int inline_index;
  62         struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
  63 };
  64
  65 extern void poll_initwait(struct poll_wqueues *pwq);
  66 extern void poll_freewait(struct poll_wqueues *pwq);
  67
  68 /*
  69  * Scaleable version of the fd_set.
  70  */
  71
  72 typedef struct {
  73         unsigned long *in, *out, *ex;
  74         unsigned long *res_in, *res_out, *res_ex;
  75 } fd_set_bits;
  76
  77 /*
  78  * How many longwords for "nr" bits?
  79  */
  80 #define FDS_BITPERLONG  (8*sizeof(long))
  81 #define FDS_LONGS(nr)   (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
  82 #define FDS_BYTES(nr)   (FDS_LONGS(nr)*sizeof(long))
  83
  84 /*
  85  * We do a VERIFY_WRITE here even though we are only reading this time:
  86  * we'll write to it eventually..
  87  *
  88  * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
  89  */
  90 static inline
  91 int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
  92 {
  93         nr = FDS_BYTES(nr);
  94         if (ufdset)
  95                 return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
  96
  97         memset(fdset, 0, nr);
  98         return 0;
  99 }
 100
 101 static inline unsigned long __must_check
 102 set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 103 {
 104         if (ufdset)
 105                 return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
 106         return 0;
 107 }
 108
 109 static inline
 110 void zero_fd_set(unsigned long nr, unsigned long *fdset)
 111 {
 112         memset(fdset, 0, FDS_BYTES(nr));
 113 }
 114
 115 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
 116
 117 extern int do_select(int n, fd_set_bits *fds, s64 *timeout);
 118 extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
 119                        s64 *timeout);
 120
 121 #endif /* KERNEL */
 122
 123 #endif /* _LINUX_POLL_H */