[linux-block.git] / include / linux / eventpoll.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *  include/linux/eventpoll.h ( Efficient event polling implementation )
 *  Copyright (C) 2001,...,2006	 Davide Libenzi
 *
 *  Davide Libenzi <davidel@xmailserver.org>
 */
#ifndef _LINUX_EVENTPOLL_H
#define _LINUX_EVENTPOLL_H

#include <uapi/linux/eventpoll.h>
#include <uapi/linux/kcmp.h>


/* Forward declarations to avoid compiler errors */
struct file;


#ifdef CONFIG_EPOLL

#ifdef CONFIG_KCMP
struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff);
#endif

/* 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(!file->f_ep))
		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);
}

int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
		 bool nonblock);

/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
static inline int ep_op_has_event(int op)
{
	return op != EPOLL_CTL_DEL;
}

#else

static inline void eventpoll_release(struct file *file) {}

#endif

#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT)
/* ARM OABI has an incompatible struct layout and needs a special handler */
extern struct epoll_event __user *
epoll_put_uevent(__poll_t revents, __u64 data,
		 struct epoll_event __user *uevent);
#else
static inline struct epoll_event __user *
epoll_put_uevent(__poll_t revents, __u64 data,
		 struct epoll_event __user *uevent)
{
	if (__put_user(revents, &uevent->events) ||
	    __put_user(data, &uevent->data))
		return NULL;

	return uevent+1;
}
#endif

#endif /* #ifndef _LINUX_EVENTPOLL_H */
Commit	Line	Data
2874c5fd	1	/* SPDX-License-Identifier: GPL-2.0-or-later */
1da177e4	2	/*
25985edc	3	* include/linux/eventpoll.h ( Efficient event polling implementation )
3419b23a	4	* Copyright (C) 2001,...,2006 Davide Libenzi
1da177e4	5	*
1da177e4	6	* Davide Libenzi <davidel@xmailserver.org>
1da177e4	7	*/
1da177e4 LT	8	#ifndef _LINUX_EVENTPOLL_H
	9	#define _LINUX_EVENTPOLL_H
	10
607ca46e	11	#include <uapi/linux/eventpoll.h>
0791e364	12	#include <uapi/linux/kcmp.h>
1da177e4	13
1da177e4 LT	14
	15	/* Forward declarations to avoid compiler errors */
	16	struct file;
	17
	18
	19	#ifdef CONFIG_EPOLL
	20
bfe3911a	21	#ifdef CONFIG_KCMP
0791e364	22	struct file get_epoll_tfile_raw_ptr(struct file file, int tfd, unsigned long toff);
92ef6da3	23	#endif
0791e364	24
1da177e4 LT	25	/* Used to release the epoll bits inside the "struct file" */
	26	void eventpoll_release_file(struct file *file);
	27
	28	/*
	29	* This is called from inside fs/file_table.c:__fput() to unlink files
	30	* from the eventpoll interface. We need to have this facility to cleanup
	31	* correctly files that are closed without being removed from the eventpoll
	32	* interface.
	33	*/
	34	static inline void eventpoll_release(struct file *file)
	35	{
	36
	37	/*
	38	* Fast check to avoid the get/release of the semaphore. Since
	39	* we're doing this outside the semaphore lock, it might return
	40	* false negatives, but we don't care. It'll help in 99.99% of cases
	41	* to avoid the semaphore lock. False positives simply cannot happen
	42	* because the file in on the way to be removed and nobody ( but
	43	* eventpoll ) has still a reference to this file.
	44	*/
319c1517	45	if (likely(!file->f_ep))
1da177e4 LT	46	return;
	47
	48	/*
	49	* The file is being closed while it is still linked to an epoll
	50	* descriptor. We need to handle this by correctly unlinking it
	51	* from its containers.
	52	*/
	53	eventpoll_release_file(file);
	54	}
	55
39220e8d JA	56	int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
	57	bool nonblock);
	58
	59	/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
	60	static inline int ep_op_has_event(int op)
	61	{
	62	return op != EPOLL_CTL_DEL;
	63	}
	64
1da177e4 LT	65	#else
1da177e4 LT	66
1da177e4 LT	67	static inline void eventpoll_release(struct file *file) {}
	68
	69	#endif
	70
249dbe74 AB	71	#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT)
	72	/* ARM OABI has an incompatible struct layout and needs a special handler */
	73	extern struct epoll_event __user *
	74	epoll_put_uevent(__poll_t revents, __u64 data,
	75	struct epoll_event __user *uevent);
	76	#else
	77	static inline struct epoll_event __user *
	78	epoll_put_uevent(__poll_t revents, __u64 data,
	79	struct epoll_event __user *uevent)
	80	{
	81	if (__put_user(revents, &uevent->events) \|\|
	82	__put_user(data, &uevent->data))
	83	return NULL;
	84
	85	return uevent+1;
	86	}
	87	#endif
	88
1da177e4	89	#endif /* #ifndef _LINUX_EVENTPOLL_H */