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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#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 (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM)
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 __poll_t _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 __poll_t poll_requested_events(const poll_table *p)
67{
68 return p ? p->_key : ~(__poll_t)0;
69}
70
71static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
72{
73 pt->_qproc = qproc;
74 pt->_key = ~(__poll_t)0; /* all events enabled */
75}
76
77static inline bool file_can_poll(struct file *file)
78{
79 return file->f_op->poll;
80}
81
82static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt)
83{
84 if (unlikely(!file->f_op->poll))
85 return DEFAULT_POLLMASK;
86 return file->f_op->poll(file, pt);
87}
88
89struct poll_table_entry {
90 struct file *filp;
91 __poll_t key;
92 wait_queue_entry_t wait;
93 wait_queue_head_t *wait_address;
94};
95
96/*
97 * Structures and helpers for select/poll syscall
98 */
99struct poll_wqueues {
100 poll_table pt;
101 struct poll_table_page *table;
102 struct task_struct *polling_task;
103 int triggered;
104 int error;
105 int inline_index;
106 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
107};
108
109extern void poll_initwait(struct poll_wqueues *pwq);
110extern void poll_freewait(struct poll_wqueues *pwq);
111extern u64 select_estimate_accuracy(struct timespec64 *tv);
112
113#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
114
115extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
116 fd_set __user *exp, struct timespec64 *end_time);
117
118extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
119 long nsec);
120
121#define __MAP(v, from, to) \
122 (from < to ? (v & from) * (to/from) : (v & from) / (from/to))
123
124static inline __u16 mangle_poll(__poll_t val)
125{
126 __u16 v = (__force __u16)val;
127#define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X)
128 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
129 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
130 M(HUP) | M(RDHUP) | M(MSG);
131#undef M
132}
133
134static inline __poll_t demangle_poll(u16 val)
135{
136#define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X)
137 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
138 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
139 M(HUP) | M(RDHUP) | M(MSG);
140#undef M
141}
142#undef __MAP
143
144
145#endif /* _LINUX_POLL_H */