xref: /freebsd-10-stable/sys/sys/eventhandler.h

/*-
 * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: head/sys/sys/eventhandler.h 107136 2002-11-21 09:17:56Z jeff $
 */

#ifndef SYS_EVENTHANDLER_H
#define SYS_EVENTHANDLER_H

#include <sys/lock.h>
#include <sys/sx.h>
#include <sys/queue.h>

struct eventhandler_entry {
	TAILQ_ENTRY(eventhandler_entry)	ee_link;
	int				ee_priority;
	void				*ee_arg;
};

struct eventhandler_list {
	char				*el_name;
	int				el_flags;
#define EHE_INITTED	(1<<0)
	struct sx			el_lock;
	TAILQ_ENTRY(eventhandler_list)	el_link;
	TAILQ_HEAD(,eventhandler_entry)	el_entries;
};

typedef struct eventhandler_entry	*eventhandler_tag;

#define	EHE_LOCK(p)	sx_xlock(&(p)->el_lock)
#define	EHE_UNLOCK(p)	sx_xunlock(&(p)->el_lock)

/*
 * Fast handler lists require the eventhandler list be present
 * at link time.  They don't allow addition of entries to
 * unknown eventhandler lists, ie. each list must have an
 * "owner".
 *
 * Fast handler lists must be defined once by the owner
 * of the eventhandler list, and the declaration must be in
 * scope at any point the list is manipulated.
 */
#define EVENTHANDLER_FAST_DECLARE(name, type)				\
extern struct eventhandler_list Xeventhandler_list_ ## name ;		\
struct eventhandler_entry_ ## name {					\
	struct eventhandler_entry	ee;				\
	type		eh_func;					\
};									\
struct __hack

#define EVENTHANDLER_FAST_DEFINE(name, type)				\
struct eventhandler_list Xeventhandler_list_ ## name = { #name };	\
struct __hack

#define EVENTHANDLER_FAST_INVOKE(name, ...)				\
do {									\
	struct eventhandler_list *_el = &Xeventhandler_list_ ## name ;	\
	struct eventhandler_entry *_ep, *_en;				\
	struct eventhandler_entry_ ## name *_t;				\
									\
	if (_el->el_flags & EHE_INITTED) {				\
		EHE_LOCK(_el);						\
		_ep = TAILQ_FIRST(&(_el->el_entries));			\
		while (_ep != NULL) {					\
			_en = TAILQ_NEXT(_ep, ee_link);			\
			_t = (struct eventhandler_entry_ ## name *)_ep; \
			_t->eh_func(_ep->ee_arg , __VA_ARGS__);		\
			_ep = _en;					\
		}							\
		EHE_UNLOCK(_el);					\
	}								\
} while (0)

#define EVENTHANDLER_FAST_REGISTER(name, func, arg, priority)		\
	eventhandler_register(&Xeventhandler_list_ ## name,		\
	#name, func, arg, priority)

#define EVENTHANDLER_FAST_DEREGISTER(name, tag)				\
	eventhandler_deregister(&Xeventhandler_list_ ## name, tag)

/*
 * Slow handlers are entirely dynamic; lists are created
 * when entries are added to them, and thus have no concept of "owner",
 *
 * Slow handlers need to be declared, but do not need to be defined. The
 * declaration must be in scope wherever the handler is to be invoked.
 */
#define EVENTHANDLER_DECLARE(name, type)				\
struct eventhandler_entry_ ## name 					\
{									\
	struct eventhandler_entry	ee;				\
	type				eh_func;			\
};									\
struct __hack

#define EVENTHANDLER_INVOKE(name, ...)					\
do {									\
	struct eventhandler_list *_el;					\
	struct eventhandler_entry *_ep, *_en;				\
	struct eventhandler_entry_ ## name *_t;				\
									\
	if (((_el = eventhandler_find_list(#name)) != NULL) && 		\
		(_el->el_flags & EHE_INITTED)) {			\
		EHE_LOCK(_el);						\
		_ep = TAILQ_FIRST(&(_el->el_entries));			\
		while (_ep != NULL) {					\
			_en = TAILQ_NEXT(_ep, ee_link);			\
			_t = (struct eventhandler_entry_ ## name *)_ep;	\
			_t->eh_func(_ep->ee_arg , __VA_ARGS__);		\
			_ep = _en;					\
		}							\
		EHE_UNLOCK(_el);					\
	}								\
} while (0)

#define EVENTHANDLER_REGISTER(name, func, arg, priority)		\
	eventhandler_register(NULL, #name, func, arg, priority)

#define EVENTHANDLER_DEREGISTER(name, tag) 				\
do {									\
	struct eventhandler_list *_el;					\
									\
	if ((_el = eventhandler_find_list(#name)) != NULL)		\
		eventhandler_deregister(_el, tag);			\
} while(0)


extern eventhandler_tag	eventhandler_register(struct eventhandler_list *list,
					      char *name,
					      void *func,
					      void *arg,
					      int priority);
extern void		eventhandler_deregister(struct eventhandler_list *list,
						eventhandler_tag tag);
extern struct eventhandler_list	*eventhandler_find_list(char *name);

/*
 * Standard system event queues.
 */

/* Shutdown events */
typedef void (*shutdown_fn)(void *, int);

#define	SHUTDOWN_PRI_FIRST	0
#define	SHUTDOWN_PRI_DEFAULT	10000
#define	SHUTDOWN_PRI_LAST	20000

EVENTHANDLER_DECLARE(shutdown_pre_sync, shutdown_fn);	/* before fs sync */
EVENTHANDLER_DECLARE(shutdown_post_sync, shutdown_fn);	/* after fs sync */
EVENTHANDLER_DECLARE(shutdown_final, shutdown_fn);

/* Idle process event */
typedef void (*idle_eventhandler_t)(void *, int);

#define IDLE_PRI_FIRST		10000
#define IDLE_PRI_LAST		20000
EVENTHANDLER_FAST_DECLARE(idle_event, idle_eventhandler_t);

/* Low memory event */
typedef void (*vm_lowmem_handler_t)(void *, int);
#define	LOWMEM_PRI_DEFAULT	0
EVENTHANDLER_DECLARE(vm_lowmem, vm_lowmem_handler_t);

#endif /* SYS_EVENTHANDLER_H */