1 #ifndef _LINUX_POLL_H 2 #define _LINUX_POLL_H 3 4 5 #include <linux/compiler.h> 6 #include <linux/ktime.h> 7 #include <linux/wait.h> 8 #include <linux/string.h> 9 #include <linux/fs.h> 10 #include <linux/sysctl.h> 11 #include <linux/uaccess.h> 12 #include <uapi/linux/poll.h> 13 14 extern struct ctl_table epoll_table[]; /* for sysctl */ 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 (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM) 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 unsigned long _key; 40 } poll_table; 41 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 */ 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 */ 64 static inline unsigned long poll_requested_events(const poll_table *p) 65 { 66 return p ? p->_key : ~0UL; 67 } 68 69 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) 70 { 71 pt->_qproc = qproc; 72 pt->_key = ~0UL; /* all events enabled */ 73 } 74 75 struct poll_table_entry { 76 struct file *filp; 77 unsigned long key; 78 wait_queue_entry_t wait; 79 wait_queue_head_t *wait_address; 80 }; 81 82 /* 83 * Structures and helpers for select/poll syscall 84 */ 85 struct poll_wqueues { 86 poll_table pt; 87 struct poll_table_page *table; 88 struct task_struct *polling_task; 89 int triggered; 90 int error; 91 int inline_index; 92 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES]; 93 }; 94 95 extern void poll_initwait(struct poll_wqueues *pwq); 96 extern void poll_freewait(struct poll_wqueues *pwq); 97 extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state, 98 ktime_t *expires, unsigned long slack); 99 extern u64 select_estimate_accuracy(struct timespec64 *tv); 100 101 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1) 102 103 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, 104 fd_set __user *exp, struct timespec64 *end_time); 105 106 extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec, 107 long nsec); 108 109 #endif /* _LINUX_POLL_H */ 110