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