1 /* $NetBSD: spinlock.h,v 1.8 2018/08/27 06:17:30 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2013 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Taylor R. Campbell. 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 _LINUX_SPINLOCK_H_ 33 #define _LINUX_SPINLOCK_H_ 34 35 #include <sys/cdefs.h> 36 #include <sys/mutex.h> 37 38 #include <machine/limits.h> 39 #include <linux/irqflags.h> 40 #include <linux/preempt.h> 41 42 #define __acquires(lock) /* XXX lockdep stuff */ 43 #define __releases(lock) /* XXX lockdep stuff */ 44 45 typedef struct spinlock { 46 kmutex_t sl_lock; 47 } spinlock_t; 48 49 static inline int 50 spin_is_locked(spinlock_t *spinlock) 51 { 52 return mutex_owned(&spinlock->sl_lock); 53 } 54 55 static inline void 56 spin_lock(spinlock_t *spinlock) 57 { 58 mutex_enter(&spinlock->sl_lock); 59 } 60 61 static inline void 62 spin_unlock(spinlock_t *spinlock) 63 { 64 mutex_exit(&spinlock->sl_lock); 65 } 66 67 static inline void 68 spin_lock_irq(spinlock_t *spinlock) 69 { 70 spin_lock(spinlock); 71 } 72 73 static inline void 74 spin_unlock_irq(spinlock_t *spinlock) 75 { 76 spin_unlock(spinlock); 77 } 78 79 /* Must be a macro because the second argument is to be assigned. */ 80 #define spin_lock_irqsave(SPINLOCK, FLAGS) \ 81 do { \ 82 (FLAGS) = 0; \ 83 mutex_enter(&((spinlock_t *)(SPINLOCK))->sl_lock); \ 84 } while (0) 85 86 static inline void 87 spin_unlock_irqrestore(spinlock_t *spinlock, unsigned long __unused flags) 88 { 89 mutex_exit(&spinlock->sl_lock); 90 } 91 92 static inline void 93 spin_lock_init(spinlock_t *spinlock) 94 { 95 /* XXX What's the right IPL? IPL_DRM...? */ 96 mutex_init(&spinlock->sl_lock, MUTEX_DEFAULT, IPL_VM); 97 } 98 99 /* 100 * XXX Linux doesn't ever destroy spin locks, it seems. We'll have to 101 * kludge it up. 102 */ 103 104 static inline void 105 spin_lock_destroy(spinlock_t *spinlock) 106 { 107 mutex_destroy(&spinlock->sl_lock); 108 } 109 110 /* This is a macro to make the panic message clearer. */ 111 #define assert_spin_locked(spinlock) \ 112 KASSERT(mutex_owned(&(spinlock)->sl_lock)) 113 114 /* 115 * Stupid reader/writer spin locks. No attempt to avoid writer 116 * starvation. Must allow recursive readers. We use mutex and state 117 * instead of compare-and-swap for expedience and LOCKDEBUG support. 118 */ 119 120 typedef struct linux_rwlock { 121 kmutex_t rw_lock; 122 unsigned rw_nreaders; 123 } rwlock_t; 124 125 static inline void 126 rwlock_init(rwlock_t *rw) 127 { 128 129 mutex_init(&rw->rw_lock, MUTEX_DEFAULT, IPL_VM); 130 rw->rw_nreaders = 0; 131 } 132 133 static inline void 134 rwlock_destroy(rwlock_t *rw) 135 { 136 137 KASSERTMSG(rw->rw_nreaders == 0, 138 "rwlock still held by %u readers", rw->rw_nreaders); 139 mutex_destroy(&rw->rw_lock); 140 } 141 142 static inline void 143 write_lock_irq(rwlock_t *rw) 144 { 145 146 for (;;) { 147 mutex_spin_enter(&rw->rw_lock); 148 if (rw->rw_nreaders == 0) 149 break; 150 mutex_spin_exit(&rw->rw_lock); 151 } 152 } 153 154 static inline void 155 write_unlock_irq(rwlock_t *rw) 156 { 157 158 KASSERT(rw->rw_nreaders == 0); 159 mutex_spin_exit(&rw->rw_lock); 160 } 161 162 static inline void 163 read_lock(rwlock_t *rw) 164 { 165 166 mutex_spin_enter(&rw->rw_lock); 167 KASSERT(rw->rw_nreaders < UINT_MAX); 168 rw->rw_nreaders++; 169 mutex_spin_exit(&rw->rw_lock); 170 } 171 172 static inline void 173 read_unlock(rwlock_t *rw) 174 { 175 176 mutex_spin_enter(&rw->rw_lock); 177 KASSERT(0 < rw->rw_nreaders); 178 rw->rw_nreaders--; 179 mutex_spin_exit(&rw->rw_lock); 180 } 181 182 #endif /* _LINUX_SPINLOCK_H_ */ 183