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 #ifdef __clang__ 20 #define MAX_STACK_ALLOC 768 21 #else 22 #define MAX_STACK_ALLOC 832 23 #endif 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)) 29 30 #define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM) 31 32 struct poll_table_struct; 33 34 /* 35 * structures and helpers for f_op->poll implementations 36 */ 37 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *); 38 39 /* 40 * Do not touch the structure directly, use the access functions 41 * poll_does_not_wait() and poll_requested_events() instead. 42 */ 43 typedef struct poll_table_struct { 44 poll_queue_proc _qproc; 45 __poll_t _key; 46 } poll_table; 47 48 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p) 49 { 50 if (p && p->_qproc && wait_address) 51 p->_qproc(filp, wait_address, p); 52 } 53 54 /* 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. 58 */ 59 static inline bool poll_does_not_wait(const poll_table *p) 60 { 61 return p == NULL || p->_qproc == NULL; 62 } 63 64 /* 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. 69 */ 70 static inline __poll_t poll_requested_events(const poll_table *p) 71 { 72 return p ? p->_key : ~(__poll_t)0; 73 } 74 75 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) 76 { 77 pt->_qproc = qproc; 78 pt->_key = ~(__poll_t)0; /* all events enabled */ 79 } 80 81 static inline bool file_can_poll(struct file *file) 82 { 83 return file->f_op->poll; 84 } 85 86 static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt) 87 { 88 if (unlikely(!file->f_op->poll)) 89 return DEFAULT_POLLMASK; 90 return file->f_op->poll(file, pt); 91 } 92 93 struct poll_table_entry { 94 struct file *filp; 95 __poll_t key; 96 wait_queue_entry_t wait; 97 wait_queue_head_t *wait_address; 98 }; 99 100 /* 101 * Structures and helpers for select/poll syscall 102 */ 103 struct poll_wqueues { 104 poll_table pt; 105 struct poll_table_page *table; 106 struct task_struct *polling_task; 107 int triggered; 108 int error; 109 int inline_index; 110 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES]; 111 }; 112 113 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); 116 117 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1) 118 119 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, 120 fd_set __user *exp, struct timespec64 *end_time); 121 122 extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec, 123 long nsec); 124 125 #define __MAP(v, from, to) \ 126 (from < to ? (v & from) * (to/from) : (v & from) / (from/to)) 127 128 static inline __u16 mangle_poll(__poll_t val) 129 { 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); 135 #undef M 136 } 137 138 static inline __poll_t demangle_poll(u16 val) 139 { 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); 144 #undef M 145 } 146 #undef __MAP 147 148 149 #endif /* _LINUX_POLL_H */ 150