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