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/sysctl.h>
12#include <linux/uaccess.h>
13#include <uapi/linux/poll.h>
14#include <uapi/linux/eventpoll.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#ifdef __clang__
20#define MAX_STACK_ALLOC 768
21#else
22#define MAX_STACK_ALLOC 832
23#endif
24#define FRONTEND_STACK_ALLOC 256
25#define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
26#define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
27#define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
28#define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
29
30#define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM)
31
32struct poll_table_struct;
33
34/*
35 * structures and helpers for f_op->poll implementations
36 */
37typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
38
39/*
40 * Do not touch the structure directly, use the access functions
41 * poll_does_not_wait() and poll_requested_events() instead.
42 */
43typedef struct poll_table_struct {
44 poll_queue_proc _qproc;
45 __poll_t _key;
46} poll_table;
47
48static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
49{
50 if (p && p->_qproc && wait_address)
51 p->_qproc(filp, wait_address, p);
52}
53
54/*
55 * Return true if it is guaranteed that poll will not wait. This is the case
56 * if the poll() of another file descriptor in the set got an event, so there
57 * is no need for waiting.
58 */
59static inline bool poll_does_not_wait(const poll_table *p)
60{
61 return p == NULL || p->_qproc == NULL;
62}
63
64/*
65 * Return the set of events that the application wants to poll for.
66 * This is useful for drivers that need to know whether a DMA transfer has
67 * to be started implicitly on poll(). You typically only want to do that
68 * if the application is actually polling for POLLIN and/or POLLOUT.
69 */
70static inline __poll_t poll_requested_events(const poll_table *p)
71{
72 return p ? p->_key : ~(__poll_t)0;
73}
74
75static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
76{
77 pt->_qproc = qproc;
78 pt->_key = ~(__poll_t)0; /* all events enabled */
79}
80
81static inline bool file_can_poll(struct file *file)
82{
83 return file->f_op->poll;
84}
85
86static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt)
87{
88 if (unlikely(!file->f_op->poll))
89 return DEFAULT_POLLMASK;
90 return file->f_op->poll(file, pt);
91}
92
93struct poll_table_entry {
94 struct file *filp;
95 __poll_t key;
96 wait_queue_entry_t wait;
97 wait_queue_head_t *wait_address;
98};
99
100/*
101 * Structures and helpers for select/poll syscall
102 */
103struct poll_wqueues {
104 poll_table pt;
105 struct poll_table_page *table;
106 struct task_struct *polling_task;
107 int triggered;
108 int error;
109 int inline_index;
110 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
111};
112
113extern void poll_initwait(struct poll_wqueues *pwq);
114extern void poll_freewait(struct poll_wqueues *pwq);
115extern u64 select_estimate_accuracy(struct timespec64 *tv);
116
117#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
118
119extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
120 fd_set __user *exp, struct timespec64 *end_time);
121
122extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
123 long nsec);
124
125#define __MAP(v, from, to) \
126 (from < to ? (v & from) * (to/from) : (v & from) / (from/to))
127
128static inline __u16 mangle_poll(__poll_t val)
129{
130 __u16 v = (__force __u16)val;
131#define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X)
132 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
133 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
134 M(HUP) | M(RDHUP) | M(MSG);
135#undef M
136}
137
138static inline __poll_t demangle_poll(u16 val)
139{
140#define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X)
141 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
142 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
143 M(HUP) | M(RDHUP) | M(MSG);
144#undef M
145}
146#undef __MAP
147
148
149#endif /* _LINUX_POLL_H */