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/*
* include/linux/eventpoll.h ( Efficent event polling implementation )
* Copyright (C) 2001,...,2006 Davide Libenzi
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Davide Libenzi <davidel@xmailserver.org>
*
*/
#ifndef _LINUX_EVENTPOLL_H
#define _LINUX_EVENTPOLL_H
#include <linux/types.h>
/* Valid opcodes to issue to sys_epoll_ctl() */
#define EPOLL_CTL_ADD 1
#define EPOLL_CTL_DEL 2
#define EPOLL_CTL_MOD 3
/* Set the One Shot behaviour for the target file descriptor */
#define EPOLLONESHOT (1 << 30)
/* Set the Edge Triggered behaviour for the target file descriptor */
#define EPOLLET (1 << 31)
/*
* On x86-64 make the 64bit structure have the same alignment as the
* 32bit structure. This makes 32bit emulation easier.
*
* UML/x86_64 needs the same packing as x86_64 - UML + UML_X86 +
* 64_BIT adds up to UML/x86_64.
*/
#ifdef __x86_64__
#define EPOLL_PACKED __attribute__((packed))
#else
#if defined(CONFIG_UML) && defined(CONFIG_UML_X86) && defined(CONFIG_64BIT)
#define EPOLL_PACKED __attribute__((packed))
#else
#define EPOLL_PACKED
#endif
#endif
struct epoll_event {
__u32 events;
__u64 data;
} EPOLL_PACKED;
#ifdef __KERNEL__
/* Forward declarations to avoid compiler errors */
struct file;
#ifdef CONFIG_EPOLL
/* Used to initialize the epoll bits inside the "struct file" */
static inline void eventpoll_init_file(struct file *file)
{
INIT_LIST_HEAD(&file->f_ep_links);
spin_lock_init(&file->f_ep_lock);
}
/* Used to release the epoll bits inside the "struct file" */
void eventpoll_release_file(struct file *file);
/*
* This is called from inside fs/file_table.c:__fput() to unlink files
* from the eventpoll interface. We need to have this facility to cleanup
* correctly files that are closed without being removed from the eventpoll
* interface.
*/
static inline void eventpoll_release(struct file *file)
{
/*
* Fast check to avoid the get/release of the semaphore. Since
* we're doing this outside the semaphore lock, it might return
* false negatives, but we don't care. It'll help in 99.99% of cases
* to avoid the semaphore lock. False positives simply cannot happen
* because the file in on the way to be removed and nobody ( but
* eventpoll ) has still a reference to this file.
*/
if (likely(list_empty(&file->f_ep_links)))
return;
/*
* The file is being closed while it is still linked to an epoll
* descriptor. We need to handle this by correctly unlinking it
* from its containers.
*/
eventpoll_release_file(file);
}
#else
static inline void eventpoll_init_file(struct file *file) {}
static inline void eventpoll_release(struct file *file) {}
#endif
#endif /* #ifdef __KERNEL__ */
#endif /* #ifndef _LINUX_EVENTPOLL_H */
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