include/linux/eventfd.h

   1 /*
   2  *  include/linux/eventfd.h
   3  *
   4  *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
   5  *
   6  */
   7
   8 #ifndef _LINUX_EVENTFD_H
   9 #define _LINUX_EVENTFD_H
  10
  11 #include <linux/fcntl.h>
  12 #include <linux/wait.h>
  13
  14 /*
  15  * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
  16  * new flags, since they might collide with O_* ones. We want
  17  * to re-use O_* flags that couldn't possibly have a meaning
  18  * from eventfd, in order to leave a free define-space for
  19  * shared O_* flags.
  20  */
  21 #define EFD_SEMAPHORE (1 << 0)
  22 #define EFD_CLOEXEC O_CLOEXEC
  23 #define EFD_NONBLOCK O_NONBLOCK
  24
  25 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
  26 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
  27
  28 struct file;
  29
  30 #ifdef CONFIG_EVENTFD
  31
  32 struct file *eventfd_file_create(unsigned int count, int flags);
  33 struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
  34 void eventfd_ctx_put(struct eventfd_ctx *ctx);
  35 struct file *eventfd_fget(int fd);
  36 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  37 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
  38 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
  39 ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
  40 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_t *wait,
  41                                   __u64 *cnt);
  42
  43 #else /* CONFIG_EVENTFD */
  44
  45 /*
  46  * Ugly ugly ugly error layer to support modules that uses eventfd but
  47  * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  48  */
  49 static inline struct file *eventfd_file_create(unsigned int count, int flags)
  50 {
  51         return ERR_PTR(-ENOSYS);
  52 }
  53
  54 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  55 {
  56         return ERR_PTR(-ENOSYS);
  57 }
  58
  59 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  60 {
  61         return -ENOSYS;
  62 }
  63
  64 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  65 {
  66
  67 }
  68
  69 static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
  70                                        __u64 *cnt)
  71 {
  72         return -ENOSYS;
  73 }
  74
  75 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  76                                                 wait_queue_t *wait, __u64 *cnt)
  77 {
  78         return -ENOSYS;
  79 }
  80
  81 #endif
  82
  83 #endif /* _LINUX_EVENTFD_H */
  84