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 #include <uapi/linux/eventpoll.h> 15 16 extern struct ctl_table epoll_table[]; /* for sysctl */ 17 /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating 18 additional memory. */ 19 #define MAX_STACK_ALLOC 832 20 #define FRONTEND_STACK_ALLOC 256 21 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC 22 #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC 23 #define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC) 24 #define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry)) 25 26 #define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM) 27 28 struct poll_table_struct; 29 30 /* 31 * structures and helpers for f_op->poll implementations 32 */ 33 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *); 34 35 /* 36 * Do not touch the structure directly, use the access functions 37 * poll_does_not_wait() and poll_requested_events() instead. 38 */ 39 typedef struct poll_table_struct { 40 poll_queue_proc _qproc; 41 __poll_t _key; 42 } poll_table; 43 44 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p) 45 { 46 if (p && p->_qproc && wait_address) 47 p->_qproc(filp, wait_address, p); 48 } 49 50 /* 51 * Return true if it is guaranteed that poll will not wait. This is the case 52 * if the poll() of another file descriptor in the set got an event, so there 53 * is no need for waiting. 54 */ 55 static inline bool poll_does_not_wait(const poll_table *p) 56 { 57 return p == NULL || p->_qproc == NULL; 58 } 59 60 /* 61 * Return the set of events that the application wants to poll for. 62 * This is useful for drivers that need to know whether a DMA transfer has 63 * to be started implicitly on poll(). You typically only want to do that 64 * if the application is actually polling for POLLIN and/or POLLOUT. 65 */ 66 static inline __poll_t poll_requested_events(const poll_table *p) 67 { 68 return p ? p->_key : ~(__poll_t)0; 69 } 70 71 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) 72 { 73 pt->_qproc = qproc; 74 pt->_key = ~(__poll_t)0; /* all events enabled */ 75 } 76 77 struct poll_table_entry { 78 struct file *filp; 79 __poll_t key; 80 wait_queue_entry_t wait; 81 wait_queue_head_t *wait_address; 82 }; 83 84 /* 85 * Structures and helpers for select/poll syscall 86 */ 87 struct poll_wqueues { 88 poll_table pt; 89 struct poll_table_page *table; 90 struct task_struct *polling_task; 91 int triggered; 92 int error; 93 int inline_index; 94 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES]; 95 }; 96 97 extern void poll_initwait(struct poll_wqueues *pwq); 98 extern void poll_freewait(struct poll_wqueues *pwq); 99 extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state, 100 ktime_t *expires, unsigned long slack); 101 extern u64 select_estimate_accuracy(struct timespec64 *tv); 102 103 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1) 104 105 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, 106 fd_set __user *exp, struct timespec64 *end_time); 107 108 extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec, 109 long nsec); 110 111 #define __MAP(v, from, to) \ 112 (from < to ? (v & from) * (to/from) : (v & from) / (from/to)) 113 114 static inline __u16 mangle_poll(__poll_t val) 115 { 116 __u16 v = (__force __u16)val; 117 #define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X) 118 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) | 119 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) | 120 M(HUP) | M(RDHUP) | M(MSG); 121 #undef M 122 } 123 124 static inline __poll_t demangle_poll(u16 val) 125 { 126 #define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X) 127 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) | 128 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) | 129 M(HUP) | M(RDHUP) | M(MSG); 130 #undef M 131 } 132 #undef __MAP 133 134 135 #endif /* _LINUX_POLL_H */ 136