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 26 struct poll_table_struct; 27 28 /* 29 * structures and helpers for f_op->poll implementations 30 */ 31 typedef 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 */ 37 typedef struct poll_table_struct { 38 poll_queue_proc _qproc; 39 __poll_t _key; 40 } poll_table; 41 poll_wait(struct file * filp,wait_queue_head_t * wait_address,poll_table * p)42 static 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 */ poll_does_not_wait(const poll_table * p)53 static 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 */ poll_requested_events(const poll_table * p)64 static inline __poll_t poll_requested_events(const poll_table *p) 65 { 66 return p ? p->_key : ~(__poll_t)0; 67 } 68 init_poll_funcptr(poll_table * pt,poll_queue_proc qproc)69 static 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 file_can_poll(struct file * file)75 static inline bool file_can_poll(struct file *file) 76 { 77 return file->f_op->poll; 78 } 79 vfs_poll(struct file * file,struct poll_table_struct * pt)80 static 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 87 struct 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 */ 97 struct 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 }; 106 107 extern void poll_initwait(struct poll_wqueues *pwq); 108 extern void poll_freewait(struct poll_wqueues *pwq); 109 extern u64 select_estimate_accuracy(struct timespec64 *tv); 110 111 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1) 112 113 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, 114 fd_set __user *exp, struct timespec64 *end_time); 115 116 extern 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 mangle_poll(__poll_t val)122 static 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 demangle_poll(u16 val)132 static 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