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