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