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 /*
  36  * Do not touch the structure directly, use the access functions
  37  * poll_does_not_wait() and poll_requested_events() instead.
  38  */
  39 typedef struct poll_table_struct {
  40         poll_queue_proc _qproc;
  41         unsigned long _key;
  42 } poll_table;
  43
  44 static 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  */
  55 static 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  */
  66 static inline unsigned long poll_requested_events(const poll_table *p)
  67 {
  68         return p ? p->_key : ~0UL;
  69 }
  70
  71 static 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
  77 struct 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  */
  87 struct 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
  97 extern void poll_initwait(struct poll_wqueues *pwq);
  98 extern void poll_freewait(struct poll_wqueues *pwq);
  99 extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
 100                                  ktime_t *expires, unsigned long slack);
 101 extern long select_estimate_accuracy(struct timespec *tv);
 102
 103
 104 static 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
 113 typedef 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  */
 131 static inline
 132 int 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
 142 static inline unsigned long __must_check
 143 set_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
 150 static inline
 151 void 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
 158 extern int do_select(int n, fd_set_bits *fds, struct timespec *end_time);
 159 extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
 160                        struct timespec *end_time);
 161 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
 162                            fd_set __user *exp, struct timespec *end_time);
 163
 164 extern int poll_select_set_timeout(struct timespec *to, long sec, long nsec);
 165
 166 #endif /* KERNEL */
 167
 168 #endif /* _LINUX_POLL_H */