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/uaccess.h> 12#include <uapi/linux/poll.h> 13#include <uapi/linux/eventpoll.h> 14 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 (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM) 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 __poll_t _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 __poll_t poll_requested_events(const poll_table *p) 65{ 66 return p ? p->_key : ~(__poll_t)0; 67} 68 69static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) 70{ 71 pt->_qproc = qproc; 72 pt->_key = ~(__poll_t)0; /* all events enabled */ 73} 74 75static inline bool file_can_poll(struct file *file) 76{ 77 return file->f_op->poll; 78} 79 80static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt) 81{ 82 if (unlikely(!file->f_op->poll)) 83 return DEFAULT_POLLMASK; 84 return file->f_op->poll(file, pt); 85} 86 87struct poll_table_entry { 88 struct file *filp; 89 __poll_t key; 90 wait_queue_entry_t wait; 91 wait_queue_head_t *wait_address; 92}; 93 94/* 95 * Structures and helpers for select/poll syscall 96 */ 97struct poll_wqueues { 98 poll_table pt; 99 struct poll_table_page *table; 100 struct task_struct *polling_task; 101 int triggered; 102 int error; 103 int inline_index; 104 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES]; 105}; 106 107extern void poll_initwait(struct poll_wqueues *pwq); 108extern void poll_freewait(struct poll_wqueues *pwq); 109extern u64 select_estimate_accuracy(struct timespec64 *tv); 110 111#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1) 112 113extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, 114 fd_set __user *exp, struct timespec64 *end_time); 115 116extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec, 117 long nsec); 118 119#define __MAP(v, from, to) \ 120 (from < to ? (v & from) * (to/from) : (v & from) / (from/to)) 121 122static inline __u16 mangle_poll(__poll_t val) 123{ 124 __u16 v = (__force __u16)val; 125#define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X) 126 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) | 127 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) | 128 M(HUP) | M(RDHUP) | M(MSG); 129#undef M 130} 131 132static inline __poll_t demangle_poll(u16 val) 133{ 134#define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X) 135 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) | 136 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) | 137 M(HUP) | M(RDHUP) | M(MSG); 138#undef M 139} 140#undef __MAP 141 142 143#endif /* _LINUX_POLL_H */ 144