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 file;
  30
  31 #ifdef CONFIG_EVENTFD
  32
  33 struct file *eventfd_file_create(unsigned int count, int flags);
  34 struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
  35 void eventfd_ctx_put(struct eventfd_ctx *ctx);
  36 struct file *eventfd_fget(int fd);
  37 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  38 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
  39 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
  40 ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
  41 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
  42                                   __u64 *cnt);
  43
  44 #else /* CONFIG_EVENTFD */
  45
  46 /*
  47  * Ugly ugly ugly error layer to support modules that uses eventfd but
  48  * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  49  */
  50 static inline struct file *eventfd_file_create(unsigned int count, int flags)
  51 {
  52         return ERR_PTR(-ENOSYS);
  53 }
  54
  55 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  56 {
  57         return ERR_PTR(-ENOSYS);
  58 }
  59
  60 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  61 {
  62         return -ENOSYS;
  63 }
  64
  65 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  66 {
  67
  68 }
  69
  70 static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
  71                                        __u64 *cnt)
  72 {
  73         return -ENOSYS;
  74 }
  75
  76 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  77                                                 wait_queue_entry_t *wait, __u64 *cnt)
  78 {
  79         return -ENOSYS;
  80 }
  81
  82 #endif
  83
  84 #endif /* _LINUX_EVENTFD_H */
  85