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
poll_wait(struct file * filp,wait_queue_head_t * wait_address,poll_table * p)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 */
poll_does_not_wait(const poll_table * p)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 */
poll_requested_events(const poll_table * p)68 static inline __poll_t poll_requested_events(const poll_table *p)
69 {
70 return p ? p->_key : ~(__poll_t)0;
71 }
72
init_poll_funcptr(poll_table * pt,poll_queue_proc qproc)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
file_can_poll(struct file * file)79 static inline bool file_can_poll(struct file *file)
80 {
81 return file->f_op->poll;
82 }
83
vfs_poll(struct file * file,struct poll_table_struct * pt)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
mangle_poll(__poll_t val)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
demangle_poll(u16 val)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