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/wait.h>
   9 #include <linux/string.h>
  10 #include <linux/mm.h>
  11 #include <asm/uaccess.h>
  12
  13
  14 struct poll_table_entry {
  15         struct file * filp;
  16         wait_queue_t wait;
  17         wait_queue_head_t * wait_address;
  18 };
  19
  20 typedef struct poll_table_struct {
  21         struct poll_table_struct * next;
  22         unsigned int nr;
  23         struct poll_table_entry * entry;
  24 } poll_table;
  25
  26 #define __MAX_POLL_TABLE_ENTRIES ((PAGE_SIZE - sizeof (poll_table)) / sizeof (struct poll_table_entry))
  27
  28 extern void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p);
  29
  30 extern inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
  31 {
  32         if (p && wait_address)
  33                 __pollwait(filp, wait_address, p);
  34 }
  35
  36 /*
  37  * For the kernel fd_set we use a fixed set-size for allocation purposes.
  38  * This set-size doesn't necessarily bear any relation to the size the user
  39  * uses, but should preferably obviously be larger than any possible user
  40  * size (NR_OPEN bits).
  41  *
  42  * We need 6 bitmaps (in/out/ex for both incoming and outgoing), and we
  43  * allocate one page for all the bitmaps. Thus we have 8*PAGE_SIZE bits,
  44  * to be divided by 6. And we'd better make sure we round to a full
  45  * long-word (in fact, we'll round to 64 bytes).
  46  */
  47
  48
  49 #define KFDS_64BLOCK ((PAGE_SIZE/(6*64))*64)
  50 #define KFDS_NR (KFDS_64BLOCK*8 > NR_OPEN ? NR_OPEN : KFDS_64BLOCK*8)
  51 typedef unsigned long kernel_fd_set[KFDS_NR/__NFDBITS];
  52
  53 /*
  54  * Scaleable version of the fd_set.
  55  */
  56
  57 typedef struct {
  58         unsigned long *in, *out, *ex;
  59         unsigned long *res_in, *res_out, *res_ex;
  60 } fd_set_bits;
  61
  62 /*
  63  * How many longwords for "nr" bits?
  64  */
  65 #define FDS_BITPERLONG  (8*sizeof(long))
  66 #define FDS_LONGS(nr)   (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
  67 #define FDS_BYTES(nr)   (FDS_LONGS(nr)*sizeof(long))
  68
  69 /*
  70  * We do a VERIFY_WRITE here even though we are only reading this time:
  71  * we'll write to it eventually..
  72  *
  73  * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
  74  */
  75 static inline
  76 int get_fd_set(unsigned long nr, void *ufdset, unsigned long *fdset)
  77 {
  78         nr = FDS_BYTES(nr);
  79         if (ufdset) {
  80                 int error;
  81                 error = verify_area(VERIFY_WRITE, ufdset, nr);
  82                 if (!error && __copy_from_user(fdset, ufdset, nr))
  83                         error = -EFAULT;
  84                 return error;
  85         }
  86         memset(fdset, 0, nr);
  87         return 0;
  88 }
  89
  90 static inline
  91 void set_fd_set(unsigned long nr, void *ufdset, unsigned long *fdset)
  92 {
  93         if (ufdset)
  94                 __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
  95 }
  96
  97 static inline
  98 void zero_fd_set(unsigned long nr, unsigned long *fdset)
  99 {
 100         memset(fdset, 0, FDS_BYTES(nr));
 101 }
 102
 103 extern int do_select(int n, fd_set_bits *fds, long *timeout);
 104
 105 #endif /* KERNEL */
 106
 107 #endif /* _LINUX_POLL_H */