5 #include <linux/compiler.h>
6 #include <linux/ktime.h>
7 #include <linux/wait.h>
8 #include <linux/string.h>
10 #include <linux/sysctl.h>
11 #include <asm/uaccess.h>
12 #include <uapi/linux/poll.h>
14 extern struct ctl_table epoll_table[]; /* for sysctl */
15 /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
18 #define MAX_STACK_ALLOC 768
20 #define MAX_STACK_ALLOC 832
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))
28 #define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
30 struct poll_table_struct;
33 * structures and helpers for f_op->poll implementations
35 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
38 * Do not touch the structure directly, use the access functions
39 * poll_does_not_wait() and poll_requested_events() instead.
41 typedef struct poll_table_struct {
42 poll_queue_proc _qproc;
46 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
48 if (p && p->_qproc && wait_address)
49 p->_qproc(filp, wait_address, p);
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.
57 static inline bool poll_does_not_wait(const poll_table *p)
59 return p == NULL || p->_qproc == NULL;
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.
68 static inline unsigned long poll_requested_events(const poll_table *p)
70 return p ? p->_key : ~0UL;
73 static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
76 pt->_key = ~0UL; /* all events enabled */
79 struct poll_table_entry {
83 wait_queue_head_t *wait_address;
87 * Structures and helpers for select/poll syscall
91 struct poll_table_page *table;
92 struct task_struct *polling_task;
96 struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
99 extern void poll_initwait(struct poll_wqueues *pwq);
100 extern void poll_freewait(struct poll_wqueues *pwq);
101 extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
102 ktime_t *expires, unsigned long slack);
103 extern u64 select_estimate_accuracy(struct timespec64 *tv);
106 static inline int poll_schedule(struct poll_wqueues *pwq, int state)
108 return poll_schedule_timeout(pwq, state, NULL, 0);
112 * Scalable version of the fd_set.
116 unsigned long *in, *out, *ex;
117 unsigned long *res_in, *res_out, *res_ex;
121 * How many longwords for "nr" bits?
123 #define FDS_BITPERLONG (8*sizeof(long))
124 #define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
125 #define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long))
128 * We do a VERIFY_WRITE here even though we are only reading this time:
129 * we'll write to it eventually..
131 * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
134 int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
138 return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
140 memset(fdset, 0, nr);
144 static inline unsigned long __must_check
145 set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
148 return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
153 void zero_fd_set(unsigned long nr, unsigned long *fdset)
155 memset(fdset, 0, FDS_BYTES(nr));
158 #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)
160 extern int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time);
161 extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
162 struct timespec64 *end_time);
163 extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
164 fd_set __user *exp, struct timespec64 *end_time);
166 extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
169 #endif /* _LINUX_POLL_H */