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