Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_POLL_H
3#define _LINUX_POLL_H
4
5
6#include <linux/compiler.h>
7#include <linux/ktime.h>
8#include <linux/wait.h>
9#include <linux/string.h>
10#include <linux/fs.h>
11#include <linux/uaccess.h>
12#include <uapi/linux/poll.h>
13#include <uapi/linux/eventpoll.h>
14
15/* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
16 additional memory. */
17#define MAX_STACK_ALLOC 832
18#define FRONTEND_STACK_ALLOC 256
19#define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
20#define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
21#define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
22#define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
23
24#define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM)
25
26struct poll_table_struct;
27
28/*
29 * structures and helpers for f_op->poll implementations
30 */
31typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
32
33/*
34 * Do not touch the structure directly, use the access function
35 * poll_requested_events() instead.
36 */
37typedef struct poll_table_struct {
38 poll_queue_proc _qproc;
39 __poll_t _key;
40} poll_table;
41
42static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
43{
44 if (p && p->_qproc) {
45 p->_qproc(filp, wait_address, p);
46 /*
47 * This memory barrier is paired in the wq_has_sleeper().
48 * See the comment above prepare_to_wait(), we need to
49 * ensure that subsequent tests in this thread can't be
50 * reordered with __add_wait_queue() in _qproc() paths.
51 */
52 smp_mb();
53 }
54}
55
56/*
57 * Return the set of events that the application wants to poll for.
58 * This is useful for drivers that need to know whether a DMA transfer has
59 * to be started implicitly on poll(). You typically only want to do that
60 * if the application is actually polling for POLLIN and/or POLLOUT.
61 */
62static inline __poll_t poll_requested_events(const poll_table *p)
63{
64 return p ? p->_key : ~(__poll_t)0;
65}
66
67static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
68{
69 pt->_qproc = qproc;
70 pt->_key = ~(__poll_t)0; /* all events enabled */
71}
72
73static inline bool file_can_poll(struct file *file)
74{
75 return file->f_op->poll;
76}
77
78static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt)
79{
80 if (unlikely(!file->f_op->poll))
81 return DEFAULT_POLLMASK;
82 return file->f_op->poll(file, pt);
83}
84
85struct poll_table_entry {
86 struct file *filp;
87 __poll_t key;
88 wait_queue_entry_t wait;
89 wait_queue_head_t *wait_address;
90};
91
92/*
93 * Structures and helpers for select/poll syscall
94 */
95struct poll_wqueues {
96 poll_table pt;
97 struct poll_table_page *table;
98 struct task_struct *polling_task;
99 int triggered;
100 int error;
101 int inline_index;
102 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
103};
104
105extern void poll_initwait(struct poll_wqueues *pwq);
106extern void poll_freewait(struct poll_wqueues *pwq);
107extern u64 select_estimate_accuracy(struct timespec64 *tv);
108
109#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
110
111extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
112 fd_set __user *exp, struct timespec64 *end_time);
113
114extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
115 long nsec);
116
117#define __MAP(v, from, to) \
118 (from < to ? (v & from) * (to/from) : (v & from) / (from/to))
119
120static inline __u16 mangle_poll(__poll_t val)
121{
122 __u16 v = (__force __u16)val;
123#define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X)
124 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
125 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
126 M(HUP) | M(RDHUP) | M(MSG);
127#undef M
128}
129
130static inline __poll_t demangle_poll(u16 val)
131{
132#define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X)
133 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
134 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
135 M(HUP) | M(RDHUP) | M(MSG);
136#undef M
137}
138#undef __MAP
139
140
141#endif /* _LINUX_POLL_H */