1b2441318SGreg Kroah-Hartman /* SPDX-License-Identifier: GPL-2.0 */
21da177e4SLinus Torvalds #ifndef _LINUX_POLL_H
31da177e4SLinus Torvalds #define _LINUX_POLL_H
41da177e4SLinus Torvalds
51da177e4SLinus Torvalds
61da177e4SLinus Torvalds #include <linux/compiler.h>
7a99bbaf5SAlexey Dobriyan #include <linux/ktime.h>
81da177e4SLinus Torvalds #include <linux/wait.h>
91da177e4SLinus Torvalds #include <linux/string.h>
10f23f6e08SAl Viro #include <linux/fs.h>
117c0f6ba6SLinus Torvalds #include <linux/uaccess.h>
12607ca46eSDavid Howells #include <uapi/linux/poll.h>
13e78cd95bSAl Viro #include <uapi/linux/eventpoll.h>
141da177e4SLinus Torvalds
1570674f95SAndi Kleen /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
1670674f95SAndi Kleen additional memory. */
1770674f95SAndi Kleen #define MAX_STACK_ALLOC 832
1870674f95SAndi Kleen #define FRONTEND_STACK_ALLOC 256
1970674f95SAndi Kleen #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
2070674f95SAndi Kleen #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
2170674f95SAndi Kleen #define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
2270674f95SAndi Kleen #define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))
2370674f95SAndi Kleen
24e78cd95bSAl Viro #define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM)
25dd23aae4SAlexey Dobriyan
261da177e4SLinus Torvalds struct poll_table_struct;
271da177e4SLinus Torvalds
281da177e4SLinus Torvalds /*
291da177e4SLinus Torvalds * structures and helpers for f_op->poll implementations
301da177e4SLinus Torvalds */
311da177e4SLinus Torvalds typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
321da177e4SLinus Torvalds
33626cf236SHans Verkuil /*
34626cf236SHans Verkuil * Do not touch the structure directly, use the access functions
35626cf236SHans Verkuil * poll_does_not_wait() and poll_requested_events() instead.
36626cf236SHans Verkuil */
371da177e4SLinus Torvalds typedef struct poll_table_struct {
38626cf236SHans Verkuil poll_queue_proc _qproc;
3901699437SAl Viro __poll_t _key;
401da177e4SLinus Torvalds } poll_table;
411da177e4SLinus Torvalds
poll_wait(struct file * filp,wait_queue_head_t * wait_address,poll_table * p)421da177e4SLinus Torvalds static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
431da177e4SLinus Torvalds {
44626cf236SHans Verkuil if (p && p->_qproc && wait_address)
45626cf236SHans Verkuil p->_qproc(filp, wait_address, p);
46626cf236SHans Verkuil }
47626cf236SHans Verkuil
48626cf236SHans Verkuil /*
49626cf236SHans Verkuil * Return true if it is guaranteed that poll will not wait. This is the case
50626cf236SHans Verkuil * if the poll() of another file descriptor in the set got an event, so there
51626cf236SHans Verkuil * is no need for waiting.
52626cf236SHans Verkuil */
poll_does_not_wait(const poll_table * p)53626cf236SHans Verkuil static inline bool poll_does_not_wait(const poll_table *p)
54626cf236SHans Verkuil {
55626cf236SHans Verkuil return p == NULL || p->_qproc == NULL;
56626cf236SHans Verkuil }
57626cf236SHans Verkuil
58626cf236SHans Verkuil /*
59626cf236SHans Verkuil * Return the set of events that the application wants to poll for.
60626cf236SHans Verkuil * This is useful for drivers that need to know whether a DMA transfer has
61626cf236SHans Verkuil * to be started implicitly on poll(). You typically only want to do that
62626cf236SHans Verkuil * if the application is actually polling for POLLIN and/or POLLOUT.
63626cf236SHans Verkuil */
poll_requested_events(const poll_table * p)6401699437SAl Viro static inline __poll_t poll_requested_events(const poll_table *p)
65626cf236SHans Verkuil {
6601699437SAl Viro return p ? p->_key : ~(__poll_t)0;
671da177e4SLinus Torvalds }
681da177e4SLinus Torvalds
init_poll_funcptr(poll_table * pt,poll_queue_proc qproc)691da177e4SLinus Torvalds static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
701da177e4SLinus Torvalds {
71626cf236SHans Verkuil pt->_qproc = qproc;
7201699437SAl Viro pt->_key = ~(__poll_t)0; /* all events enabled */
731da177e4SLinus Torvalds }
741da177e4SLinus Torvalds
file_can_poll(struct file * file)753deb642fSChristoph Hellwig static inline bool file_can_poll(struct file *file)
769965ed17SChristoph Hellwig {
77*a11e1d43SLinus Torvalds return file->f_op->poll;
789965ed17SChristoph Hellwig }
799965ed17SChristoph Hellwig
vfs_poll(struct file * file,struct poll_table_struct * pt)80*a11e1d43SLinus Torvalds static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt)
81*a11e1d43SLinus Torvalds {
82*a11e1d43SLinus Torvalds if (unlikely(!file->f_op->poll))
83*a11e1d43SLinus Torvalds return DEFAULT_POLLMASK;
84*a11e1d43SLinus Torvalds return file->f_op->poll(file, pt);
85*a11e1d43SLinus Torvalds }
863deb642fSChristoph Hellwig
8770674f95SAndi Kleen struct poll_table_entry {
8870674f95SAndi Kleen struct file *filp;
89ddc0505fSAl Viro __poll_t key;
90ac6424b9SIngo Molnar wait_queue_entry_t wait;
9170674f95SAndi Kleen wait_queue_head_t *wait_address;
9270674f95SAndi Kleen };
9370674f95SAndi Kleen
941da177e4SLinus Torvalds /*
95dac36dd8SNamhyung Kim * Structures and helpers for select/poll syscall
961da177e4SLinus Torvalds */
971da177e4SLinus Torvalds struct poll_wqueues {
981da177e4SLinus Torvalds poll_table pt;
991da177e4SLinus Torvalds struct poll_table_page *table;
1005f820f64STejun Heo struct task_struct *polling_task;
1015f820f64STejun Heo int triggered;
1021da177e4SLinus Torvalds int error;
10370674f95SAndi Kleen int inline_index;
10470674f95SAndi Kleen struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
1051da177e4SLinus Torvalds };
1061da177e4SLinus Torvalds
1071da177e4SLinus Torvalds extern void poll_initwait(struct poll_wqueues *pwq);
1081da177e4SLinus Torvalds extern void poll_freewait(struct poll_wqueues *pwq);
109766b9f92SDeepa Dinamani extern u64 select_estimate_accuracy(struct timespec64 *tv);
11095aac7b1SShawn Bohrer
1119f72949fSDavid Woodhouse #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
1129f72949fSDavid Woodhouse
113a2dcb44cSAl Viro extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
114766b9f92SDeepa Dinamani fd_set __user *exp, struct timespec64 *end_time);
1151da177e4SLinus Torvalds
116766b9f92SDeepa Dinamani extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
117766b9f92SDeepa Dinamani long nsec);
118b773ad40SThomas Gleixner
1197a163b21SAl Viro #define __MAP(v, from, to) \
1207a163b21SAl Viro (from < to ? (v & from) * (to/from) : (v & from) / (from/to))
1217a163b21SAl Viro
mangle_poll(__poll_t val)1227a163b21SAl Viro static inline __u16 mangle_poll(__poll_t val)
1237a163b21SAl Viro {
1247a163b21SAl Viro __u16 v = (__force __u16)val;
1257a163b21SAl Viro #define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X)
1267a163b21SAl Viro return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
1277a163b21SAl Viro M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
1287a163b21SAl Viro M(HUP) | M(RDHUP) | M(MSG);
1297a163b21SAl Viro #undef M
1307a163b21SAl Viro }
1317a163b21SAl Viro
demangle_poll(u16 val)1327a163b21SAl Viro static inline __poll_t demangle_poll(u16 val)
1337a163b21SAl Viro {
1347a163b21SAl Viro #define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X)
1357a163b21SAl Viro return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) |
1367a163b21SAl Viro M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) |
1377a163b21SAl Viro M(HUP) | M(RDHUP) | M(MSG);
1387a163b21SAl Viro #undef M
1397a163b21SAl Viro }
1407a163b21SAl Viro #undef __MAP
1417a163b21SAl Viro
1427a163b21SAl Viro
1431da177e4SLinus Torvalds #endif /* _LINUX_POLL_H */
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