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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 /*
     22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 #ifndef _SYS_MUTEX_H
     27 #define	_SYS_MUTEX_H
     28 
     29 #ifndef	_ASM
     30 #include <sys/types.h>
     31 #endif
     32 
     33 #ifdef	__cplusplus
     34 extern "C" {
     35 #endif
     36 
     37 #ifndef	_ASM
     38 
     39 /*
     40  * Public interface to mutual exclusion locks.  See mutex(9F) for details.
     41  *
     42  * The basic mutex type is MUTEX_ADAPTIVE, which is expected to be used
     43  * in almost all of the kernel.  MUTEX_SPIN provides interrupt blocking
     44  * and must be used in interrupt handlers above LOCK_LEVEL.  The iblock
     45  * cookie argument to mutex_init() encodes the interrupt level to block.
     46  * The iblock cookie must be NULL for adaptive locks.
     47  *
     48  * MUTEX_DEFAULT is the type usually specified (except in drivers) to
     49  * mutex_init().  It is identical to MUTEX_ADAPTIVE.
     50  *
     51  * MUTEX_DRIVER is always used by drivers.  mutex_init() converts this to
     52  * either MUTEX_ADAPTIVE or MUTEX_SPIN depending on the iblock cookie.
     53  *
     54  * Mutex statistics can be gathered on the fly, without rebooting or
     55  * recompiling the kernel, via the lockstat driver (lockstat(7D)).
     56  */
     57 typedef enum {
     58 	MUTEX_ADAPTIVE = 0,	/* spin if owner is running, otherwise block */
     59 	MUTEX_SPIN = 1,		/* block interrupts and spin */
     60 	MUTEX_DRIVER = 4,	/* driver (DDI) mutex */
     61 	MUTEX_DEFAULT = 6	/* kernel default mutex */
     62 } kmutex_type_t;
     63 
     64 typedef struct mutex {
     65 #ifdef _LP64
     66 	void	*_opaque[1];
     67 #else
     68 	void	*_opaque[2];
     69 #endif
     70 } kmutex_t;
     71 
     72 #ifdef _KERNEL
     73 
     74 #define	MUTEX_HELD(x)		(mutex_owned(x))
     75 #define	MUTEX_NOT_HELD(x)	(!mutex_owned(x) || panicstr || quiesce_active)
     76 
     77 extern	void	mutex_init(kmutex_t *, char *, kmutex_type_t, void *);
     78 extern	void	mutex_destroy(kmutex_t *);
     79 extern	void	mutex_enter(kmutex_t *);
     80 extern	int	mutex_tryenter(kmutex_t *);
     81 extern	void	mutex_exit(kmutex_t *);
     82 extern	int	mutex_owned(const kmutex_t *);
     83 extern	struct _kthread *mutex_owner(const kmutex_t *);
     84 
     85 extern  ushort_t mutex_backoff_base;
     86 extern  uint_t mutex_backoff_cap;
     87 extern  ushort_t mutex_cap_factor;
     88 extern  uchar_t mutex_backoff_shift;
     89 extern  void (*mutex_lock_delay)(uint_t);
     90 extern  uint_t (*mutex_lock_backoff)(uint_t);
     91 extern  void (*mutex_delay)(void);
     92 extern  void mutex_delay_default(void);
     93 extern  void mutex_sync(void);
     94 
     95 extern	void default_lock_delay(uint_t);
     96 extern	uint_t default_lock_backoff(uint_t);
     97 
     98 #endif	/* _KERNEL */
     99 
    100 #endif	/* _ASM */
    101 
    102 #ifdef	__cplusplus
    103 }
    104 #endif
    105 
    106 #endif	/* _SYS_MUTEX_H */
    107