projects/linux·blob v4.8 · refs

165 lines · 4.5 KiB

1#ifndef _LINUX_POLL_H
2#define _LINUX_POLL_H
3
4
5#include <linux/compiler.h>
6#include <linux/ktime.h>
7#include <linux/wait.h>
8#include <linux/string.h>
9#include <linux/fs.h>
10#include <linux/sysctl.h>
11#include <asm/uaccess.h>
12#include <uapi/linux/poll.h>
13
14extern struct ctl_table epoll_table[]; /* for sysctl */
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 (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
25
26struct poll_table_struct;
27
28/*
29 * structures and helpers for f_op->poll implementations
30 */
31typedef 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 */
37typedef struct poll_table_struct {
38 poll_queue_proc _qproc;
39 unsigned long _key;
40} poll_table;
41
42static 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 */
53static 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 */
64static inline unsigned long poll_requested_events(const poll_table *p)
65{
66 return p ? p->_key : ~0UL;
67}
68
69static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
70{
71 pt->_qproc = qproc;
72 pt->_key = ~0UL; /* all events enabled */
73}
74
75struct poll_table_entry {
76 struct file *filp;
77 unsigned long key;
78 wait_queue_t wait;
79 wait_queue_head_t *wait_address;
80};
81
82/*
83 * Structures and helpers for select/poll syscall
84 */
85struct poll_wqueues {
86 poll_table pt;
87 struct poll_table_page *table;
88 struct task_struct *polling_task;
89 int triggered;
90 int error;
91 int inline_index;
92 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
93};
94
95extern void poll_initwait(struct poll_wqueues *pwq);
96extern void poll_freewait(struct poll_wqueues *pwq);
97extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
98 ktime_t *expires, unsigned long slack);
99extern u64 select_estimate_accuracy(struct timespec64 *tv);
100
101
102static inline int poll_schedule(struct poll_wqueues *pwq, int state)
103{
104 return poll_schedule_timeout(pwq, state, NULL, 0);
105}
106
107/*
108 * Scalable version of the fd_set.
109 */
110
111typedef struct {
112 unsigned long *in, *out, *ex;
113 unsigned long *res_in, *res_out, *res_ex;
114} fd_set_bits;
115
116/*
117 * How many longwords for "nr" bits?
118 */
119#define FDS_BITPERLONG (8*sizeof(long))
120#define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
121#define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long))
122
123/*
124 * We do a VERIFY_WRITE here even though we are only reading this time:
125 * we'll write to it eventually..
126 *
127 * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
128 */
129static inline
130int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
131{
132 nr = FDS_BYTES(nr);
133 if (ufdset)
134 return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
135
136 memset(fdset, 0, nr);
137 return 0;
138}
139
140static inline unsigned long __must_check
141set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
142{
143 if (ufdset)
144 return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
145 return 0;
146}
147
148static inline
149void zero_fd_set(unsigned long nr, unsigned long *fdset)
150{
151 memset(fdset, 0, FDS_BYTES(nr));
152}
153
154#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
155
156extern int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time);
157extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
158 struct timespec64 *end_time);
159extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
160 fd_set __user *exp, struct timespec64 *end_time);
161
162extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
163 long nsec);
164
165#endif /* _LINUX_POLL_H */