[mirror_ubuntu-zesty-kernel.git] / include / linux / eventpoll.h

/*
 *  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 */
Commit	Line	Data
1da177e4	1	/*
25985edc	2	* include/linux/eventpoll.h ( Efficient event polling implementation )
3419b23a	3	* Copyright (C) 2001,...,2006 Davide Libenzi
1da177e4 LT	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation; either version 2 of the License, or
	8	* (at your option) any later version.
	9	*
	10	* Davide Libenzi <davidel@xmailserver.org>
	11	*
	12	*/
	13
	14	#ifndef _LINUX_EVENTPOLL_H
	15	#define _LINUX_EVENTPOLL_H
	16
a0998b50 UD	17	/* For O_CLOEXEC */
a0998b50 UD	18	#include <linux/fcntl.h>
1da177e4 LT	19	#include <linux/types.h>
1da177e4 LT	20
9fe5ad9c	21	/* Flags for epoll_create1. */
a0998b50	22	#define EPOLL_CLOEXEC O_CLOEXEC
1da177e4 LT	23
	24	/* Valid opcodes to issue to sys_epoll_ctl() */
	25	#define EPOLL_CTL_ADD 1
	26	#define EPOLL_CTL_DEL 2
	27	#define EPOLL_CTL_MOD 3
03a7beb5	28	#define EPOLL_CTL_DISABLE 4
1da177e4	29
4d7e30d9 AH	30	/*
	31	* Request the handling of system wakeup events so as to prevent system suspends
	32	* from happening while those events are being processed.
	33	*
	34	* Assuming neither EPOLLET nor EPOLLONESHOT is set, system suspends will not be
	35	* re-allowed until epoll_wait is called again after consuming the wakeup
	36	* event(s).
	37	*
d9914cf6	38	* Requires CAP_BLOCK_SUSPEND
4d7e30d9 AH	39	*/
	40	#define EPOLLWAKEUP (1 << 29)
	41
1da177e4 LT	42	/* Set the One Shot behaviour for the target file descriptor */
	43	#define EPOLLONESHOT (1 << 30)
	44
	45	/* Set the Edge Triggered behaviour for the target file descriptor */
	46	#define EPOLLET (1 << 31)
	47
	48	/*
	49	* On x86-64 make the 64bit structure have the same alignment as the
	50	* 32bit structure. This makes 32bit emulation easier.
d75e26a8	51	*
ca5cd877	52	* UML/x86_64 needs the same packing as x86_64
1da177e4 LT	53	*/
	54	#ifdef __x86_64__
	55	#define EPOLL_PACKED __attribute__((packed))
	56	#else
	57	#define EPOLL_PACKED
	58	#endif
	59
	60	struct epoll_event {
	61	__u32 events;
	62	__u64 data;
	63	} EPOLL_PACKED;
	64
	65	#ifdef __KERNEL__
	66
	67	/* Forward declarations to avoid compiler errors */
	68	struct file;
	69
	70
	71	#ifdef CONFIG_EPOLL
	72
	73	/* Used to initialize the epoll bits inside the "struct file" */
5a6b7951 BL	74	static inline void eventpoll_init_file(struct file *file)
	75	{
	76	INIT_LIST_HEAD(&file->f_ep_links);
28d82dc1	77	INIT_LIST_HEAD(&file->f_tfile_llink);
5a6b7951 BL	78	}
5a6b7951 BL	79
1da177e4 LT	80
	81	/* Used to release the epoll bits inside the "struct file" */
	82	void eventpoll_release_file(struct file *file);
	83
	84	/*
	85	* This is called from inside fs/file_table.c:__fput() to unlink files
	86	* from the eventpoll interface. We need to have this facility to cleanup
	87	* correctly files that are closed without being removed from the eventpoll
	88	* interface.
	89	*/
	90	static inline void eventpoll_release(struct file *file)
	91	{
	92
	93	/*
	94	* Fast check to avoid the get/release of the semaphore. Since
	95	* we're doing this outside the semaphore lock, it might return
	96	* false negatives, but we don't care. It'll help in 99.99% of cases
	97	* to avoid the semaphore lock. False positives simply cannot happen
	98	* because the file in on the way to be removed and nobody ( but
	99	* eventpoll ) has still a reference to this file.
	100	*/
	101	if (likely(list_empty(&file->f_ep_links)))
	102	return;
	103
	104	/*
	105	* The file is being closed while it is still linked to an epoll
	106	* descriptor. We need to handle this by correctly unlinking it
	107	* from its containers.
	108	*/
	109	eventpoll_release_file(file);
	110	}
	111
1da177e4 LT	112	#else
	113
	114	static inline void eventpoll_init_file(struct file *file) {}
	115	static inline void eventpoll_release(struct file *file) {}
	116
	117	#endif
	118
	119	#endif /* #ifdef __KERNEL__ */
	120
	121	#endif /* #ifndef _LINUX_EVENTPOLL_H */
	122