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/wait.h>
  13 #include <linux/err.h>
  14 #include <linux/percpu-defs.h>
  15 #include <linux/percpu.h>
  16 #include <linux/sched.h>
  17 #include <uapi/linux/eventfd.h>
  18
  19 /*
  20  * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
  21  * new flags, since they might collide with O_* ones. We want
  22  * to re-use O_* flags that couldn't possibly have a meaning
  23  * from eventfd, in order to leave a free define-space for
  24  * shared O_* flags.
  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);
  39 __u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
  40 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
  41                                   __u64 *cnt);
  42 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
  43
  44 static inline bool eventfd_signal_allowed(void)
  45 {
  46         return !current->in_eventfd;
  47 }
  48
  49 #else /* CONFIG_EVENTFD */
  50
  51 /*
  52  * Ugly ugly ugly error layer to support modules that uses eventfd but
  53  * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  54  */
  55
  56 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  57 {
  58         return ERR_PTR(-ENOSYS);
  59 }
  60
  61 static inline int eventfd_signal(struct eventfd_ctx *ctx)
  62 {
  63         return -ENOSYS;
  64 }
  65
  66 static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
  67 {
  68         return -ENOSYS;
  69 }
  70
  71 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  72 {
  73
  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 static inline bool eventfd_signal_allowed(void)
  83 {
  84         return true;
  85 }
  86
  87 static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
  88 {
  89
  90 }
  91
  92 #endif
  93
  94 #endif /* _LINUX_EVENTFD_H */
  95