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mutex.h revision 1.12 
      1 /*	$NetBSD: mutex.h,v 1.12 2017/09/24 07:39:28 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2002, 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 and Andrew Doran.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef _HPPA_MUTEX_H_
     33 #define	_HPPA_MUTEX_H_
     34 
     35 /*
     36  * The HPPA mutex implementation is troublesome, because HPPA lacks
     37  * a compare-and-set operation, yet there are many SMP HPPA machines
     38  * in circulation.  SMP for spin mutexes is easy - we don't need to
     39  * know who owns the lock.  For adaptive mutexes, we need an owner
     40  * field and additional interlock
     41  */
     42 
     43 #ifndef __ASSEMBLER__
     44 
     45 #include <machine/lock.h>
     46 
     47 struct kmutex {
     48 	union {
     49 		/*
     50 		 * Only the 16 bytes aligned word of __cpu_simple_lock_t will
     51 		 * be used. It's 16 bytes to simplify the allocation.
     52 		 * See hppa/lock.h
     53 		 */
     54 #ifdef __MUTEX_PRIVATE
     55 		struct {
     56 			__cpu_simple_lock_t	mtxu_lock;	/* 0-15 */
     57 			volatile uint32_t	mtxs_owner;	/* 16-19 */
     58 			ipl_cookie_t		mtxs_ipl;	/* 20-23 */
     59 			volatile uint8_t	mtxs_waiters;	/* 24 */
     60 
     61 			/* For LOCKDEBUG */
     62 			uint8_t			mtxs_dodebug;	/* 25 */
     63 		} s;
     64 #endif
     65 		uint8_t			mtxu_pad[32];	/* 0 - 32 */
     66 	} u;
     67 } __aligned (16);
     68 #endif
     69 
     70 #ifdef __MUTEX_PRIVATE
     71 
     72 #define	__HAVE_MUTEX_STUBS	1
     73 
     74 #define	mtx_lock	u.s.mtxu_lock
     75 #define	mtx_owner	u.s.mtxs_owner
     76 #define	mtx_ipl		u.s.mtxs_ipl
     77 #define	mtx_waiters	u.s.mtxs_waiters
     78 #define	mtx_dodebug	u.s.mtxs_dodebug
     79 
     80 /* Magic constants for mtx_owner */
     81 #define	MUTEX_ADAPTIVE_UNOWNED		0xffffff00
     82 #define	MUTEX_SPIN_FLAG			0xffffff10
     83 #define	MUTEX_UNOWNED_OR_SPIN(x)	(((x) & 0xffffffef) == 0xffffff00)
     84 
     85 #ifndef __ASSEMBLER__
     86 
     87 static inline uintptr_t
     88 MUTEX_OWNER(uintptr_t owner)
     89 {
     90 	return owner;
     91 }
     92 
     93 static inline int
     94 MUTEX_OWNED(uintptr_t owner)
     95 {
     96 	return owner != MUTEX_ADAPTIVE_UNOWNED;
     97 }
     98 
     99 static inline int
    100 MUTEX_SET_WAITERS(struct kmutex *mtx, uintptr_t owner)
    101 {
    102 	mb_write();
    103 	mtx->mtx_waiters = 1;
    104 	mb_memory();
    105 	return mtx->mtx_owner != MUTEX_ADAPTIVE_UNOWNED;
    106 }
    107 
    108 static inline int
    109 MUTEX_HAS_WAITERS(const volatile struct kmutex *mtx)
    110 {
    111 	return mtx->mtx_waiters != 0;
    112 }
    113 
    114 static inline void
    115 MUTEX_INITIALIZE_SPIN(struct kmutex *mtx, bool dodebug, int ipl)
    116 {
    117 	mtx->mtx_ipl = makeiplcookie(ipl);
    118 	mtx->mtx_dodebug = dodebug;
    119 	mtx->mtx_owner = MUTEX_SPIN_FLAG;
    120 	__cpu_simple_lock_init(&mtx->mtx_lock);
    121 }
    122 
    123 static inline void
    124 MUTEX_INITIALIZE_ADAPTIVE(struct kmutex *mtx, bool dodebug)
    125 {
    126 	mtx->mtx_dodebug = dodebug;
    127 	mtx->mtx_owner = MUTEX_ADAPTIVE_UNOWNED;
    128 	__cpu_simple_lock_init(&mtx->mtx_lock);
    129 }
    130 
    131 static inline void
    132 MUTEX_DESTROY(struct kmutex *mtx)
    133 {
    134 	mtx->mtx_owner = 0xffffffff;
    135 }
    136 
    137 static inline bool
    138 MUTEX_DEBUG_P(const volatile struct kmutex *mtx)
    139 {
    140 	return mtx->mtx_dodebug != 0;
    141 }
    142 
    143 static inline int
    144 MUTEX_SPIN_P(volatile struct kmutex *mtx)
    145 {
    146 	return mtx->mtx_owner == MUTEX_SPIN_FLAG;
    147 }
    148 
    149 static inline int
    150 MUTEX_ADAPTIVE_P(volatile struct kmutex *mtx)
    151 {
    152 	return mtx->mtx_owner != MUTEX_SPIN_FLAG;
    153 }
    154 
    155 /* Acquire an adaptive mutex */
    156 static inline int
    157 MUTEX_ACQUIRE(struct kmutex *mtx, uintptr_t curthread)
    158 {
    159 	if (!__cpu_simple_lock_try(&mtx->mtx_lock))
    160 		return 0;
    161 	mtx->mtx_owner = curthread;
    162 	return 1;
    163 }
    164 
    165 /* Release an adaptive mutex */
    166 static inline void
    167 MUTEX_RELEASE(struct kmutex *mtx)
    168 {
    169 	mtx->mtx_owner = MUTEX_ADAPTIVE_UNOWNED;
    170 	__cpu_simple_unlock(&mtx->mtx_lock);
    171 	mtx->mtx_waiters = 0;
    172 }
    173 
    174 static inline void
    175 MUTEX_CLEAR_WAITERS(struct kmutex *mtx)
    176 {
    177 	mtx->mtx_waiters = 0;
    178 }
    179 
    180 #endif	/* __ASSEMBLER__ */
    181 
    182 #endif	/* __MUTEX_PRIVATE */
    183 
    184 #endif /* _HPPA_MUTEX_H_ */
    185