Linux kernel mirror (for testing)
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linux
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
16extern 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
28struct poll_table_struct;
29
30/*
31 * structures and helpers for f_op->poll implementations
32 */
33typedef 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 */
39typedef struct poll_table_struct {
40 poll_queue_proc _qproc;
41 unsigned long _key;
42} poll_table;
43
44static 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 */
55static 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 */
66static inline unsigned long poll_requested_events(const poll_table *p)
67{
68 return p ? p->_key : ~0UL;
69}
70
71static 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
77struct 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 */
87struct 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
97extern void poll_initwait(struct poll_wqueues *pwq);
98extern void poll_freewait(struct poll_wqueues *pwq);
99extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
100 ktime_t *expires, unsigned long slack);
101extern long select_estimate_accuracy(struct timespec *tv);
102
103
104static 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
113typedef 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 */
131static inline
132int 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
142static inline unsigned long __must_check
143set_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
150static inline
151void 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
158extern int do_select(int n, fd_set_bits *fds, struct timespec *end_time);
159extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
160 struct timespec *end_time);
161extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
162 fd_set __user *exp, struct timespec *end_time);
163
164extern int poll_select_set_timeout(struct timespec *to, long sec, long nsec);
165
166#endif /* KERNEL */
167
168#endif /* _LINUX_POLL_H */