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 | |