1 /* SPDX-License-Identifier: GPL-2.0 */
6 #include <linux/compiler.h>
7 #include <linux/ktime.h>
8 #include <linux/wait.h>
9 #include <linux/string.h>
11 #include <linux/sysctl.h>
12 #include <linux/uaccess.h>
13 #include <uapi/linux/poll.h>
14 #include <uapi/linux/eventpoll.h>
16 extern struct ctl_table epoll_table
[]; /* for sysctl */
17 /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
20 #define MAX_STACK_ALLOC 768
22 #define MAX_STACK_ALLOC 832
24 #define FRONTEND_STACK_ALLOC 256
25 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
26 #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
27 #define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
28 #define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
30 #define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM)
32 struct poll_table_struct
;
35 * structures and helpers for f_op->poll implementations
37 typedef void (*poll_queue_proc
)(struct file
*, wait_queue_head_t
*, struct poll_table_struct
*);
40 * Do not touch the structure directly, use the access functions
41 * poll_does_not_wait() and poll_requested_events() instead.
43 typedef struct poll_table_struct
{
44 poll_queue_proc _qproc
;
48 static inline void poll_wait(struct file
* filp
, wait_queue_head_t
* wait_address
, poll_table
*p
)
50 if (p
&& p
->_qproc
&& wait_address
)
51 p
->_qproc(filp
, wait_address
, p
);
55 * Return true if it is guaranteed that poll will not wait. This is the case
56 * if the poll() of another file descriptor in the set got an event, so there
57 * is no need for waiting.
59 static inline bool poll_does_not_wait(const poll_table
*p
)
61 return p
== NULL
|| p
->_qproc
== NULL
;
65 * Return the set of events that the application wants to poll for.
66 * This is useful for drivers that need to know whether a DMA transfer has
67 * to be started implicitly on poll(). You typically only want to do that
68 * if the application is actually polling for POLLIN and/or POLLOUT.
70 static inline __poll_t
poll_requested_events(const poll_table
*p
)
72 return p
? p
->_key
: ~(__poll_t
)0;
75 static inline void init_poll_funcptr(poll_table
*pt
, poll_queue_proc qproc
)
78 pt
->_key
= ~(__poll_t
)0; /* all events enabled */
81 static inline bool file_can_poll(struct file
*file
)
83 return file
->f_op
->poll
;
86 static inline __poll_t
vfs_poll(struct file
*file
, struct poll_table_struct
*pt
)
88 if (unlikely(!file
->f_op
->poll
))
89 return DEFAULT_POLLMASK
;
90 return file
->f_op
->poll(file
, pt
);
93 struct poll_table_entry
{
96 wait_queue_entry_t wait
;
97 wait_queue_head_t
*wait_address
;
101 * Structures and helpers for select/poll syscall
103 struct poll_wqueues
{
105 struct poll_table_page
*table
;
106 struct task_struct
*polling_task
;
110 struct poll_table_entry inline_entries
[N_INLINE_POLL_ENTRIES
];
113 extern void poll_initwait(struct poll_wqueues
*pwq
);
114 extern void poll_freewait(struct poll_wqueues
*pwq
);
115 extern u64
select_estimate_accuracy(struct timespec64
*tv
);
117 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
119 extern int core_sys_select(int n
, fd_set __user
*inp
, fd_set __user
*outp
,
120 fd_set __user
*exp
, struct timespec64
*end_time
);
122 extern int poll_select_set_timeout(struct timespec64
*to
, time64_t sec
,
125 #define __MAP(v, from, to) \
126 (from < to ? (v & from) * (to/from) : (v & from) / (from/to))
128 static inline __u16
mangle_poll(__poll_t val
)
130 __u16 v
= (__force __u16
)val
;
131 #define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X)
132 return M(IN
) | M(OUT
) | M(PRI
) | M(ERR
) | M(NVAL
) |
133 M(RDNORM
) | M(RDBAND
) | M(WRNORM
) | M(WRBAND
) |
134 M(HUP
) | M(RDHUP
) | M(MSG
);
138 static inline __poll_t
demangle_poll(u16 val
)
140 #define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X)
141 return M(IN
) | M(OUT
) | M(PRI
) | M(ERR
) | M(NVAL
) |
142 M(RDNORM
) | M(RDBAND
) | M(WRNORM
) | M(WRBAND
) |
143 M(HUP
) | M(RDHUP
) | M(MSG
);
149 #endif /* _LINUX_POLL_H */