mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-27 06:34:11 +08:00
03a7beb55b
Enhanced epoll_ctl to support EPOLL_CTL_DISABLE, which disables an epoll item. If epoll_ctl doesn't return -EBUSY in this case, it is then safe to delete the epoll item in a multi-threaded environment. Also added a new test_epoll self- test app to both demonstrate the need for this feature and test it. Signed-off-by: Paton J. Lewis <palewis@adobe.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Jason Baron <jbaron@redhat.com> Cc: Paul Holland <pholland@adobe.com> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
123 lines
3.2 KiB
C
123 lines
3.2 KiB
C
/*
|
|
* include/linux/eventpoll.h ( Efficient 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
|
|
|
|
/* For O_CLOEXEC */
|
|
#include <linux/fcntl.h>
|
|
#include <linux/types.h>
|
|
|
|
/* Flags for epoll_create1. */
|
|
#define EPOLL_CLOEXEC O_CLOEXEC
|
|
|
|
/* Valid opcodes to issue to sys_epoll_ctl() */
|
|
#define EPOLL_CTL_ADD 1
|
|
#define EPOLL_CTL_DEL 2
|
|
#define EPOLL_CTL_MOD 3
|
|
#define EPOLL_CTL_DISABLE 4
|
|
|
|
/*
|
|
* Request the handling of system wakeup events so as to prevent system suspends
|
|
* from happening while those events are being processed.
|
|
*
|
|
* Assuming neither EPOLLET nor EPOLLONESHOT is set, system suspends will not be
|
|
* re-allowed until epoll_wait is called again after consuming the wakeup
|
|
* event(s).
|
|
*
|
|
* Requires CAP_BLOCK_SUSPEND
|
|
*/
|
|
#define EPOLLWAKEUP (1 << 29)
|
|
|
|
/* 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
|
|
*/
|
|
#ifdef __x86_64__
|
|
#define EPOLL_PACKED __attribute__((packed))
|
|
#else
|
|
#define EPOLL_PACKED
|
|
#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);
|
|
INIT_LIST_HEAD(&file->f_tfile_llink);
|
|
}
|
|
|
|
|
|
/* 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 */
|
|
|