eventfd.h 1.72 KB
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
 *  include/linux/eventfd.h
 *
 *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
 *
 */

#ifndef _LINUX_EVENTFD_H
#define _LINUX_EVENTFD_H

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#include <linux/fcntl.h>
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#include <linux/wait.h>
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#include <linux/err.h>
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/*
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 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
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 * new flags, since they might collide with O_* ones. We want
 * to re-use O_* flags that couldn't possibly have a meaning
 * from eventfd, in order to leave a free define-space for
 * shared O_* flags.
 */
#define EFD_SEMAPHORE (1 << 0)
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#define EFD_CLOEXEC O_CLOEXEC
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#define EFD_NONBLOCK O_NONBLOCK
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#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)

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struct eventfd_ctx;
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struct file;

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#ifdef CONFIG_EVENTFD

void eventfd_ctx_put(struct eventfd_ctx *ctx);
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struct file *eventfd_fget(int fd);
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struct eventfd_ctx *eventfd_ctx_fdget(int fd);
struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
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__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
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int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
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				  __u64 *cnt);
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#else /* CONFIG_EVENTFD */

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/*
 * Ugly ugly ugly error layer to support modules that uses eventfd but
 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
 */
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static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
{
	return ERR_PTR(-ENOSYS);
}

static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
{
	return -ENOSYS;
}

static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
{

}
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static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
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						wait_queue_entry_t *wait, __u64 *cnt)
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{
	return -ENOSYS;
}

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#endif
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#endif /* _LINUX_EVENTFD_H */