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
  16 extern 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
  28 struct poll_table_struct;
  29
  30 /*
  31  * structures and helpers for f_op->poll implementations
  32  */
  33 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
  34
  35 typedef struct poll_table_struct {
  36         poll_queue_proc qproc;
  37         unsigned long key;
  38 } poll_table;
  39
  40 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
  41 {
  42         if (p && wait_address)
  43                 p->qproc(filp, wait_address, p);
  44 }
  45
  46 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
  47 {
  48         pt->qproc = qproc;
  49         pt->key   = ~0UL; /* all events enabled */
  50 }
  51
  52 struct poll_table_entry {
  53         struct file *filp;
  54         unsigned long key;
  55         wait_queue_t wait;
  56         wait_queue_head_t *wait_address;
  57 };
  58
  59 /*
  60  * Structures and helpers for select/poll syscall
  61  */
  62 struct poll_wqueues {
  63         poll_table pt;
  64         struct poll_table_page *table;
  65         struct task_struct *polling_task;
  66         int triggered;
  67         int error;
  68         int inline_index;
  69         struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
  70 };
  71
  72 extern void poll_initwait(struct poll_wqueues *pwq);
  73 extern void poll_freewait(struct poll_wqueues *pwq);
  74 extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
  75                                  ktime_t *expires, unsigned long slack);
  76 extern long select_estimate_accuracy(struct timespec *tv);
  77
  78
  79 static inline int poll_schedule(struct poll_wqueues *pwq, int state)
  80 {
  81         return poll_schedule_timeout(pwq, state, NULL, 0);
  82 }
  83
  84 /*
  85  * Scalable version of the fd_set.
  86  */
  87
  88 typedef struct {
  89         unsigned long *in, *out, *ex;
  90         unsigned long *res_in, *res_out, *res_ex;
  91 } fd_set_bits;
  92
  93 /*
  94  * How many longwords for "nr" bits?
  95  */
  96 #define FDS_BITPERLONG  (8*sizeof(long))
  97 #define FDS_LONGS(nr)   (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
  98 #define FDS_BYTES(nr)   (FDS_LONGS(nr)*sizeof(long))
  99
 100 /*
 101  * We do a VERIFY_WRITE here even though we are only reading this time:
 102  * we'll write to it eventually..
 103  *
 104  * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
 105  */
 106 static inline
 107 int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 108 {
 109         nr = FDS_BYTES(nr);
 110         if (ufdset)
 111                 return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
 112
 113         memset(fdset, 0, nr);
 114         return 0;
 115 }
 116
 117 static inline unsigned long __must_check
 118 set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 119 {
 120         if (ufdset)
 121                 return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
 122         return 0;
 123 }
 124
 125 static inline
 126 void zero_fd_set(unsigned long nr, unsigned long *fdset)
 127 {
 128         memset(fdset, 0, FDS_BYTES(nr));
 129 }
 130
 131 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
 132
 133 extern int do_select(int n, fd_set_bits *fds, struct timespec *end_time);
 134 extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
 135                        struct timespec *end_time);
 136 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
 137                            fd_set __user *exp, struct timespec *end_time);
 138
 139 extern int poll_select_set_timeout(struct timespec *to, long sec, long nsec);
 140
 141 #endif /* KERNEL */
 142
 143 #endif /* _LINUX_POLL_H */