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      1 /*	$NetBSD: lock.h,v 1.94 2024/05/12 10:45:13 rillig Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1999, 2000, 2006, 2007 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      9  * NASA Ames Research Center, by Ross Harvey, and by Andrew Doran.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     30  * POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 #ifndef	_SYS_LOCK_H_
     34 #define	_SYS_LOCK_H_
     35 
     36 #include <sys/stdint.h>
     37 #include <sys/mutex.h>
     38 
     39 #include <machine/lock.h>
     40 
     41 #ifdef _KERNEL
     42 
     43 #ifdef _KERNEL_OPT
     44 #include "opt_lockdebug.h"
     45 #endif
     46 
     47 /*
     48  * From <machine/lock.h>.
     49  */
     50 #ifndef SPINLOCK_SPIN_HOOK
     51 #define	SPINLOCK_SPIN_HOOK
     52 #endif
     53 #ifndef SPINLOCK_BACKOFF_HOOK
     54 #include <sys/systm.h>
     55 #define	SPINLOCK_BACKOFF_HOOK		nullop(NULL)
     56 #endif
     57 #ifndef	SPINLOCK_BACKOFF_MIN
     58 #define	SPINLOCK_BACKOFF_MIN	4
     59 #endif
     60 #ifndef	SPINLOCK_BACKOFF_MAX
     61 #define	SPINLOCK_BACKOFF_MAX	128
     62 #endif
     63 
     64 #define	SPINLOCK_BACKOFF(count)					\
     65 do {								\
     66 	int __i;						\
     67 	for (__i = (count); __i != 0; __i--) {			\
     68 		SPINLOCK_BACKOFF_HOOK;				\
     69 	}							\
     70 	if ((count) < SPINLOCK_BACKOFF_MAX)			\
     71 		(count) += (count);				\
     72 } while (0)
     73 
     74 #ifdef LOCKDEBUG
     75 #define	SPINLOCK_SPINOUT(spins)		((spins)++ > 0x0fffffff)
     76 #else
     77 #define	SPINLOCK_SPINOUT(spins)		((void)(spins), 0)
     78 #endif
     79 
     80 extern __cpu_simple_lock_t kernel_lock[];
     81 
     82 #endif /* _KERNEL */
     83 
     84 #endif /* _SYS_LOCK_H_ */
     85