LXR linux/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#include <linux/err.h>
  15#include <linux/percpu-defs.h>
  16#include <linux/percpu.h>
  17#include <linux/sched.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_SEMAPHORE (1 << 0)
  27#define EFD_CLOEXEC O_CLOEXEC
  28#define EFD_NONBLOCK O_NONBLOCK
  29
  30#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
  31#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
  32
  33struct eventfd_ctx;
  34struct file;
  35
  36#ifdef CONFIG_EVENTFD
  37
  38void eventfd_ctx_put(struct eventfd_ctx *ctx);
  39struct file *eventfd_fget(int fd);
  40struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  41struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
  42__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
  43int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
  44                                  __u64 *cnt);
  45void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
  46
  47static inline bool eventfd_signal_allowed(void)
  48{
  49        return !current->in_eventfd_signal;
  50}
  51
  52#else /* CONFIG_EVENTFD */
  53
  54/*
  55 * Ugly ugly ugly error layer to support modules that uses eventfd but
  56 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  57 */
  58
  59static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  60{
  61        return ERR_PTR(-ENOSYS);
  62}
  63
  64static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  65{
  66        return -ENOSYS;
  67}
  68
  69static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  70{
  71
  72}
  73
  74static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  75                                                wait_queue_entry_t *wait, __u64 *cnt)
  76{
  77        return -ENOSYS;
  78}
  79
  80static inline bool eventfd_signal_allowed(void)
  81{
  82        return true;
  83}
  84
  85static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
  86{
  87
  88}
  89
  90#endif
  91
  92#endif /* _LINUX_EVENTFD_H */
  93
  94