xref: /illumos-gate/usr/src/lib/libfakekernel/common/sys/mutex.h (revision bbf21555)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
 * Copyright 2017 RackTop Systems.
 */

#ifndef _SYS_MUTEX_H
#define	_SYS_MUTEX_H

#include <sys/synch.h>	/* lwp_mutex_t */

#ifdef	__cplusplus
extern "C" {
#endif

/*
 * Public interface to mutual exclusion locks.  See mutex(9F) for details.
 *
 * The basic mutex type is MUTEX_ADAPTIVE, which is expected to be used
 * in almost all of the kernel.  MUTEX_SPIN provides interrupt blocking
 * and must be used in interrupt handlers above LOCK_LEVEL.  The iblock
 * cookie argument to mutex_init() encodes the interrupt level to block.
 * The iblock cookie must be NULL for adaptive locks.
 *
 * MUTEX_DEFAULT is the type usually specified (except in drivers) to
 * mutex_init().  It is identical to MUTEX_ADAPTIVE.
 *
 * MUTEX_DRIVER is always used by drivers.  mutex_init() converts this to
 * either MUTEX_ADAPTIVE or MUTEX_SPIN depending on the iblock cookie.
 *
 * Mutex statistics can be gathered on the fly, without rebooting or
 * recompiling the kernel, via the lockstat driver (lockstat(4D)).
 */
typedef enum {
	MUTEX_ADAPTIVE = 0,	/* spin if owner is running, otherwise block */
	MUTEX_SPIN = 1,		/* block interrupts and spin */
	MUTEX_DRIVER = 4,	/* driver (DDI) mutex */
	MUTEX_DEFAULT = 6	/* kernel default mutex */
} kmutex_type_t;

struct _kmutex {
	lwp_mutex_t m_lock;
	void *m_owner;
};
typedef struct _kmutex kmutex_t;

#if defined(_KERNEL) || defined(_FAKE_KERNEL)
/* See the real sys/mutex.h */
typedef struct pad_mutex {
	kmutex_t	pad_mutex;
#ifdef _LP64
	char		pad_pad[64 - sizeof (kmutex_t)];
#endif
} pad_mutex_t;
#endif	/* _KERNEL */

extern char *volatile panicstr;  /* panic string pointer */

#define	MUTEX_HELD(x)		(mutex_owned(x))
#define	MUTEX_NOT_HELD(x)	(!mutex_owned(x) || panicstr)

/*
 * We're simulating the kernel mutex API here, and the
 * user-level has a different signature, so rename.
 */
#define	mutex_init	kmutex_init
#define	mutex_destroy	kmutex_destroy

/*
 * We want to avoid binding against the versions of these
 * functions in libc which causes bad things to happen.
 */
#define	mutex_enter	kmutex_enter
#define	mutex_exit	kmutex_exit

extern	void	kmutex_init(kmutex_t *, char *, kmutex_type_t, void *);
extern	void	kmutex_destroy(kmutex_t *);

extern	void	kmutex_enter(kmutex_t *);
extern	void	kmutex_exit(kmutex_t *);

extern	int	mutex_tryenter(kmutex_t *);
extern	int	mutex_owned(const kmutex_t *);

extern	void *mutex_owner(const kmutex_t *);

#ifdef	__cplusplus
}
#endif

#endif	/* _SYS_MUTEX_H */