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
15 extern struct ctl_table epoll_table[]; /* for sysctl */
16 /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
17 additional memory. */
18 #ifdef __clang__
19 #define MAX_STACK_ALLOC 768
20 #else
21 #define MAX_STACK_ALLOC 832
22 #endif
23 #define FRONTEND_STACK_ALLOC 256
24 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
25 #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
26 #define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
27 #define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
28
29 #define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
30
31 struct poll_table_struct;
32
33 /*
34 * structures and helpers for f_op->poll implementations
35 */
36 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
37
38 /*
39 * Do not touch the structure directly, use the access functions
40 * poll_does_not_wait() and poll_requested_events() instead.
41 */
42 typedef struct poll_table_struct {
43 poll_queue_proc _qproc;
44 unsigned long _key;
45 } poll_table;
46
poll_wait(struct file * filp,wait_queue_head_t * wait_address,poll_table * p)47 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
48 {
49 if (p && p->_qproc && wait_address)
50 p->_qproc(filp, wait_address, p);
51 }
52
53 /*
54 * Return true if it is guaranteed that poll will not wait. This is the case
55 * if the poll() of another file descriptor in the set got an event, so there
56 * is no need for waiting.
57 */
poll_does_not_wait(const poll_table * p)58 static inline bool poll_does_not_wait(const poll_table *p)
59 {
60 return p == NULL || p->_qproc == NULL;
61 }
62
63 /*
64 * Return the set of events that the application wants to poll for.
65 * This is useful for drivers that need to know whether a DMA transfer has
66 * to be started implicitly on poll(). You typically only want to do that
67 * if the application is actually polling for POLLIN and/or POLLOUT.
68 */
poll_requested_events(const poll_table * p)69 static inline unsigned long poll_requested_events(const poll_table *p)
70 {
71 return p ? p->_key : ~0UL;
72 }
73
init_poll_funcptr(poll_table * pt,poll_queue_proc qproc)74 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
75 {
76 pt->_qproc = qproc;
77 pt->_key = ~0UL; /* all events enabled */
78 }
79
80 struct poll_table_entry {
81 struct file *filp;
82 unsigned long key;
83 wait_queue_entry_t wait;
84 wait_queue_head_t *wait_address;
85 };
86
87 /*
88 * Structures and helpers for select/poll syscall
89 */
90 struct poll_wqueues {
91 poll_table pt;
92 struct poll_table_page *table;
93 struct task_struct *polling_task;
94 int triggered;
95 int error;
96 int inline_index;
97 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
98 };
99
100 extern void poll_initwait(struct poll_wqueues *pwq);
101 extern void poll_freewait(struct poll_wqueues *pwq);
102 extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
103 ktime_t *expires, unsigned long slack);
104 extern u64 select_estimate_accuracy(struct timespec64 *tv);
105
106 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
107
108 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
109 fd_set __user *exp, struct timespec64 *end_time);
110
111 extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
112 long nsec);
113
114 #endif /* _LINUX_POLL_H */
115