include/linux/eventfd.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *  include/linux/eventfd.h
   4  *
   5  *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
   6  *
   7  */
   8
   9 #ifndef _LINUX_EVENTFD_H
  10 #define _LINUX_EVENTFD_H
  11
  12 #include <linux/fcntl.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 struct eventfd_ctx;
  30 struct file;
  31
  32 #ifdef CONFIG_EVENTFD
  33
  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 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_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
  49 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  50 {
  51         return ERR_PTR(-ENOSYS);
  52 }
  53
  54 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  55 {
  56         return -ENOSYS;
  57 }
  58
  59 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  60 {
  61
  62 }
  63
  64 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  65                                                 wait_queue_entry_t *wait, __u64 *cnt)
  66 {
  67         return -ENOSYS;
  68 }
  69
  70 #endif
  71
  72 #endif /* _LINUX_EVENTFD_H */
  73