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 #include <uapi/linux/eventpoll.h>
15
16 extern struct ctl_table epoll_table[]; /* for sysctl */
17 /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
18 additional memory. */
19 #define MAX_STACK_ALLOC 832
20 #define FRONTEND_STACK_ALLOC 256
21 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
22 #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
23 #define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
24 #define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
25
26 #define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM)
27
28 struct poll_table_struct;
29
30 /*
31 * structures and helpers for f_op->poll implementations
32 */
33 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
34
35 /*
36 * Do not touch the structure directly, use the access functions
37 * poll_does_not_wait() and poll_requested_events() instead.
38 */
39 typedef struct poll_table_struct {
40 poll_queue_proc _qproc;
41 __poll_t _key;
42 } poll_table;
43
poll_wait(struct file * filp,wait_queue_head_t * wait_address,poll_table * p)44 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
45 {
46 if (p && p->_qproc && wait_address)
47 p->_qproc(filp, wait_address, p);
48 }
49
50 /*
51 * Return true if it is guaranteed that poll will not wait. This is the case
52 * if the poll() of another file descriptor in the set got an event, so there
53 * is no need for waiting.
54 */
poll_does_not_wait(const poll_table * p)55 static inline bool poll_does_not_wait(const poll_table *p)
56 {
57 return p == NULL || p->_qproc == NULL;
58 }
59
60 /*
61 * Return the set of events that the application wants to poll for.
62 * This is useful for drivers that need to know whether a DMA transfer has
63 * to be started implicitly on poll(). You typically only want to do that
64 * if the application is actually polling for POLLIN and/or POLLOUT.
65 */
poll_requested_events(const poll_table * p)66 static inline __poll_t poll_requested_events(const poll_table *p)
67 {
68 return p ? p->_key : ~(__poll_t)0;
69 }
70
init_poll_funcptr(poll_table * pt,poll_queue_proc qproc)71 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
72 {
73 pt->_qproc = qproc;
74 pt->_key = ~(__poll_t)0; /* all events enabled */
75 }
76
file_can_poll(struct file * file)77 static inline bool file_can_poll(struct file *file)
78 {
79 return file->f_op->poll;
80 }
81
vfs_poll(struct file * file,struct poll_table_struct * pt)82 static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt)
83 {
84 if (unlikely(!file->f_op->poll))
85 return DEFAULT_POLLMASK;
86 return file->f_op->poll(file, pt);
87 }
88
89 struct poll_table_entry {
90 struct file *filp;
91 __poll_t key;
92 wait_queue_entry_t wait;
93 wait_queue_head_t *wait_address;
94 };
95
96 /*
97 * Structures and helpers for select/poll syscall
98 */
99 struct poll_wqueues {
100 poll_table pt;
101 struct poll_table_page *table;
102 struct task_struct *polling_task;
103 int triggered;
104 int error;
105 int inline_index;
106 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
107 };
108
109 extern void poll_initwait(struct poll_wqueues *pwq);
110 extern void poll_freewait(struct poll_wqueues *pwq);
111 extern u64 select_estimate_accuracy(struct timespec64 *tv);
112
113 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
114
115 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
116 fd_set __user *exp, struct timespec64 *end_time);
117
118 extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
119 long nsec);
120
121 #define __MAP(v, from, to) \
122 (from < to ? (v & from) * (to/from) : (v & from) / (from/to))
123
mangle_poll(__poll_t val)124 static inline __u16 mangle_poll(__poll_t val)
125 {
126 __u16 v = (__force __u16)val;
127 #define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X)
128 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
129 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
130 M(HUP) | M(RDHUP) | M(MSG);
131 #undef M
132 }
133
demangle_poll(u16 val)134 static inline __poll_t demangle_poll(u16 val)
135 {
136 #define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X)
137 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
138 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
139 M(HUP) | M(RDHUP) | M(MSG);
140 #undef M
141 }
142 #undef __MAP
143
144
145 #endif /* _LINUX_POLL_H */
146
