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6849991490
This lock moves out of the CONFIG_EPOLL ifdef and becomes f_lock. For now, epoll remains the only user, but a future patch will use it to protect f_flags as well. Cc: Davide Libenzi <davidel@xmailserver.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
109 lines
2.8 KiB
C
109 lines
2.8 KiB
C
/*
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* include/linux/eventpoll.h ( Efficent event polling implementation )
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* Copyright (C) 2001,...,2006 Davide Libenzi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* Davide Libenzi <davidel@xmailserver.org>
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*
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*/
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#ifndef _LINUX_EVENTPOLL_H
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#define _LINUX_EVENTPOLL_H
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/* For O_CLOEXEC */
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#include <linux/fcntl.h>
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#include <linux/types.h>
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/* Flags for epoll_create1. */
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#define EPOLL_CLOEXEC O_CLOEXEC
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/* Valid opcodes to issue to sys_epoll_ctl() */
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#define EPOLL_CTL_ADD 1
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#define EPOLL_CTL_DEL 2
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#define EPOLL_CTL_MOD 3
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/* Set the One Shot behaviour for the target file descriptor */
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#define EPOLLONESHOT (1 << 30)
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/* Set the Edge Triggered behaviour for the target file descriptor */
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#define EPOLLET (1 << 31)
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/*
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* On x86-64 make the 64bit structure have the same alignment as the
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* 32bit structure. This makes 32bit emulation easier.
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*
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* UML/x86_64 needs the same packing as x86_64
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*/
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#ifdef __x86_64__
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#define EPOLL_PACKED __attribute__((packed))
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#else
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#define EPOLL_PACKED
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#endif
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struct epoll_event {
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__u32 events;
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__u64 data;
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} EPOLL_PACKED;
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#ifdef __KERNEL__
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/* Forward declarations to avoid compiler errors */
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struct file;
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#ifdef CONFIG_EPOLL
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/* Used to initialize the epoll bits inside the "struct file" */
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static inline void eventpoll_init_file(struct file *file)
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{
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INIT_LIST_HEAD(&file->f_ep_links);
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}
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/* Used to release the epoll bits inside the "struct file" */
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void eventpoll_release_file(struct file *file);
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/*
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* This is called from inside fs/file_table.c:__fput() to unlink files
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* from the eventpoll interface. We need to have this facility to cleanup
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* correctly files that are closed without being removed from the eventpoll
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* interface.
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*/
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static inline void eventpoll_release(struct file *file)
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{
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/*
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* Fast check to avoid the get/release of the semaphore. Since
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* we're doing this outside the semaphore lock, it might return
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* false negatives, but we don't care. It'll help in 99.99% of cases
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* to avoid the semaphore lock. False positives simply cannot happen
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* because the file in on the way to be removed and nobody ( but
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* eventpoll ) has still a reference to this file.
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*/
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if (likely(list_empty(&file->f_ep_links)))
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return;
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/*
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* The file is being closed while it is still linked to an epoll
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* descriptor. We need to handle this by correctly unlinking it
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* from its containers.
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*/
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eventpoll_release_file(file);
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}
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#else
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static inline void eventpoll_init_file(struct file *file) {}
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static inline void eventpoll_release(struct file *file) {}
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#endif
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#endif /* #ifdef __KERNEL__ */
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#endif /* #ifndef _LINUX_EVENTPOLL_H */
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