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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
15extern struct ctl_table epoll_table[]; /* for sysctl */
16/* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
17 additional memory. */
18#define MAX_STACK_ALLOC 832
19#define FRONTEND_STACK_ALLOC 256
20#define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
21#define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
22#define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
23#define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
24
25#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
26
27struct poll_table_struct;
28
29/*
30 * structures and helpers for f_op->poll implementations
31 */
32typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
33
34/*
35 * Do not touch the structure directly, use the access functions
36 * poll_does_not_wait() and poll_requested_events() instead.
37 */
38typedef struct poll_table_struct {
39 poll_queue_proc _qproc;
40 unsigned long _key;
41} poll_table;
42
43static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
44{
45 if (p && p->_qproc && wait_address)
46 p->_qproc(filp, wait_address, p);
47}
48
49/*
50 * Return true if it is guaranteed that poll will not wait. This is the case
51 * if the poll() of another file descriptor in the set got an event, so there
52 * is no need for waiting.
53 */
54static inline bool poll_does_not_wait(const poll_table *p)
55{
56 return p == NULL || p->_qproc == NULL;
57}
58
59/*
60 * Return the set of events that the application wants to poll for.
61 * This is useful for drivers that need to know whether a DMA transfer has
62 * to be started implicitly on poll(). You typically only want to do that
63 * if the application is actually polling for POLLIN and/or POLLOUT.
64 */
65static inline unsigned long poll_requested_events(const poll_table *p)
66{
67 return p ? p->_key : ~0UL;
68}
69
70static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
71{
72 pt->_qproc = qproc;
73 pt->_key = ~0UL; /* all events enabled */
74}
75
76struct poll_table_entry {
77 struct file *filp;
78 unsigned long key;
79 wait_queue_entry_t wait;
80 wait_queue_head_t *wait_address;
81};
82
83/*
84 * Structures and helpers for select/poll syscall
85 */
86struct poll_wqueues {
87 poll_table pt;
88 struct poll_table_page *table;
89 struct task_struct *polling_task;
90 int triggered;
91 int error;
92 int inline_index;
93 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
94};
95
96extern void poll_initwait(struct poll_wqueues *pwq);
97extern void poll_freewait(struct poll_wqueues *pwq);
98extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
99 ktime_t *expires, unsigned long slack);
100extern u64 select_estimate_accuracy(struct timespec64 *tv);
101
102#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
103
104extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
105 fd_set __user *exp, struct timespec64 *end_time);
106
107extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
108 long nsec);
109
110#endif /* _LINUX_POLL_H */