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 #ifdef __clang__ 18 #define MAX_STACK_ALLOC 768 19 #else 20 #define MAX_STACK_ALLOC 832 21 #endif 22 #define FRONTEND_STACK_ALLOC 256 23 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC 24 #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC 25 #define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC) 26 #define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry)) 27 28 #define DEFAULT_POLLMASK (EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM) 29 30 struct poll_table_struct; 31 32 /* 33 * structures and helpers for f_op->poll implementations 34 */ 35 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *); 36 37 /* 38 * Do not touch the structure directly, use the access functions 39 * poll_does_not_wait() and poll_requested_events() instead. 40 */ 41 typedef struct poll_table_struct { 42 poll_queue_proc _qproc; 43 __poll_t _key; 44 } poll_table; 45 46 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p) 47 { 48 if (p && p->_qproc && wait_address) 49 p->_qproc(filp, wait_address, p); 50 } 51 52 /* 53 * Return true if it is guaranteed that poll will not wait. This is the case 54 * if the poll() of another file descriptor in the set got an event, so there 55 * is no need for waiting. 56 */ 57 static inline bool poll_does_not_wait(const poll_table *p) 58 { 59 return p == NULL || p->_qproc == NULL; 60 } 61 62 /* 63 * Return the set of events that the application wants to poll for. 64 * This is useful for drivers that need to know whether a DMA transfer has 65 * to be started implicitly on poll(). You typically only want to do that 66 * if the application is actually polling for POLLIN and/or POLLOUT. 67 */ 68 static inline __poll_t poll_requested_events(const poll_table *p) 69 { 70 return p ? p->_key : ~(__poll_t)0; 71 } 72 73 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) 74 { 75 pt->_qproc = qproc; 76 pt->_key = ~(__poll_t)0; /* all events enabled */ 77 } 78 79 static inline bool file_can_poll(struct file *file) 80 { 81 return file->f_op->poll; 82 } 83 84 static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt) 85 { 86 if (unlikely(!file->f_op->poll)) 87 return DEFAULT_POLLMASK; 88 return file->f_op->poll(file, pt); 89 } 90 91 struct poll_table_entry { 92 struct file *filp; 93 __poll_t key; 94 wait_queue_entry_t wait; 95 wait_queue_head_t *wait_address; 96 }; 97 98 /* 99 * Structures and helpers for select/poll syscall 100 */ 101 struct poll_wqueues { 102 poll_table pt; 103 struct poll_table_page *table; 104 struct task_struct *polling_task; 105 int triggered; 106 int error; 107 int inline_index; 108 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES]; 109 }; 110 111 extern void poll_initwait(struct poll_wqueues *pwq); 112 extern void poll_freewait(struct poll_wqueues *pwq); 113 extern u64 select_estimate_accuracy(struct timespec64 *tv); 114 115 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1) 116 117 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, 118 fd_set __user *exp, struct timespec64 *end_time); 119 120 extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec, 121 long nsec); 122 123 #define __MAP(v, from, to) \ 124 (from < to ? (v & from) * (to/from) : (v & from) / (from/to)) 125 126 static inline __u16 mangle_poll(__poll_t val) 127 { 128 __u16 v = (__force __u16)val; 129 #define M(X) __MAP(v, (__force __u16)EPOLL##X, POLL##X) 130 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) | 131 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) | 132 M(HUP) | M(RDHUP) | M(MSG); 133 #undef M 134 } 135 136 static inline __poll_t demangle_poll(u16 val) 137 { 138 #define M(X) (__force __poll_t)__MAP(val, POLL##X, (__force __u16)EPOLL##X) 139 return M(IN) | M(OUT) | M(PRI) | M(ERR) | M(NVAL) | 140 M(RDNORM) | M(RDBAND) | M(WRNORM) | M(WRBAND) | 141 M(HUP) | M(RDHUP) | M(MSG); 142 #undef M 143 } 144 #undef __MAP 145 146 147 #endif /* _LINUX_POLL_H */ 148