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 void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
  39 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
  40                                   __u64 *cnt);
  41 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
  42
  43 static inline bool eventfd_signal_allowed(void)
  44 {
  45         return !current->in_eventfd;
  46 }
  47
  48 #else /* CONFIG_EVENTFD */
  49
  50 /*
  51  * Ugly ugly ugly error layer to support modules that uses eventfd but
  52  * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  53  */
  54
  55 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  56 {
  57         return ERR_PTR(-ENOSYS);
  58 }
  59
  60 static inline void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
  61 {
  62 }
  63
  64 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  65 {
  66
  67 }
  68
  69 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  70                                                 wait_queue_entry_t *wait, __u64 *cnt)
  71 {
  72         return -ENOSYS;
  73 }
  74
  75 static inline bool eventfd_signal_allowed(void)
  76 {
  77         return true;
  78 }
  79
  80 static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
  81 {
  82
  83 }
  84
  85 #endif
  86
  87 static inline void eventfd_signal(struct eventfd_ctx *ctx)
  88 {
  89         eventfd_signal_mask(ctx, 0);
  90 }
  91
  92 #endif /* _LINUX_EVENTFD_H */
  93