| 1 | /* $NetBSD: spinlock.h,v 1.7 2016/04/13 08:43:56 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 | |
| 40 | #define __acquires(lock) /* XXX lockdep stuff */ |
| 41 | #define __releases(lock) /* XXX lockdep stuff */ |
| 42 | |
| 43 | typedef struct spinlock { |
| 44 | kmutex_t sl_lock; |
| 45 | } spinlock_t; |
| 46 | |
| 47 | static inline int |
| 48 | spin_is_locked(spinlock_t *spinlock) |
| 49 | { |
| 50 | return mutex_owned(&spinlock->sl_lock); |
| 51 | } |
| 52 | |
| 53 | static inline void |
| 54 | spin_lock(spinlock_t *spinlock) |
| 55 | { |
| 56 | mutex_enter(&spinlock->sl_lock); |
| 57 | } |
| 58 | |
| 59 | static inline void |
| 60 | spin_unlock(spinlock_t *spinlock) |
| 61 | { |
| 62 | mutex_exit(&spinlock->sl_lock); |
| 63 | } |
| 64 | |
| 65 | static inline void |
| 66 | spin_lock_irq(spinlock_t *spinlock) |
| 67 | { |
| 68 | spin_lock(spinlock); |
| 69 | } |
| 70 | |
| 71 | static inline void |
| 72 | spin_unlock_irq(spinlock_t *spinlock) |
| 73 | { |
| 74 | spin_unlock(spinlock); |
| 75 | } |
| 76 | |
| 77 | /* Must be a macro because the second argument is to be assigned. */ |
| 78 | #define spin_lock_irqsave(SPINLOCK, FLAGS) \ |
| 79 | do { \ |
| 80 | (FLAGS) = 0; \ |
| 81 | mutex_enter(&((spinlock_t *)(SPINLOCK))->sl_lock); \ |
| 82 | } while (0) |
| 83 | |
| 84 | static inline void |
| 85 | spin_unlock_irqrestore(spinlock_t *spinlock, unsigned long __unused flags) |
| 86 | { |
| 87 | mutex_exit(&spinlock->sl_lock); |
| 88 | } |
| 89 | |
| 90 | static inline void |
| 91 | spin_lock_init(spinlock_t *spinlock) |
| 92 | { |
| 93 | /* XXX What's the right IPL? IPL_DRM...? */ |
| 94 | mutex_init(&spinlock->sl_lock, MUTEX_DEFAULT, IPL_VM); |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * XXX Linux doesn't ever destroy spin locks, it seems. We'll have to |
| 99 | * kludge it up. |
| 100 | */ |
| 101 | |
| 102 | static inline void |
| 103 | spin_lock_destroy(spinlock_t *spinlock) |
| 104 | { |
| 105 | mutex_destroy(&spinlock->sl_lock); |
| 106 | } |
| 107 | |
| 108 | /* This is a macro to make the panic message clearer. */ |
| 109 | #define assert_spin_locked(spinlock) \ |
| 110 | KASSERT(mutex_owned(&(spinlock)->sl_lock)) |
| 111 | |
| 112 | /* |
| 113 | * Stupid reader/writer spin locks. No attempt to avoid writer |
| 114 | * starvation. Must allow recursive readers. We use mutex and state |
| 115 | * instead of compare-and-swap for expedience and LOCKDEBUG support. |
| 116 | */ |
| 117 | |
| 118 | typedef struct linux_rwlock { |
| 119 | kmutex_t rw_lock; |
| 120 | unsigned rw_nreaders; |
| 121 | } rwlock_t; |
| 122 | |
| 123 | static inline void |
| 124 | rwlock_init(rwlock_t *rw) |
| 125 | { |
| 126 | |
| 127 | mutex_init(&rw->rw_lock, MUTEX_DEFAULT, IPL_VM); |
| 128 | rw->rw_nreaders = 0; |
| 129 | } |
| 130 | |
| 131 | static inline void |
| 132 | rwlock_destroy(rwlock_t *rw) |
| 133 | { |
| 134 | |
| 135 | KASSERTMSG(rw->rw_nreaders == 0, |
| 136 | "rwlock still held by %u readers" , rw->rw_nreaders); |
| 137 | mutex_destroy(&rw->rw_lock); |
| 138 | } |
| 139 | |
| 140 | static inline void |
| 141 | write_lock_irq(rwlock_t *rw) |
| 142 | { |
| 143 | |
| 144 | for (;;) { |
| 145 | mutex_spin_enter(&rw->rw_lock); |
| 146 | if (rw->rw_nreaders == 0) |
| 147 | break; |
| 148 | mutex_spin_exit(&rw->rw_lock); |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | static inline void |
| 153 | write_unlock_irq(rwlock_t *rw) |
| 154 | { |
| 155 | |
| 156 | KASSERT(rw->rw_nreaders == 0); |
| 157 | mutex_spin_exit(&rw->rw_lock); |
| 158 | } |
| 159 | |
| 160 | static inline void |
| 161 | read_lock(rwlock_t *rw) |
| 162 | { |
| 163 | |
| 164 | mutex_spin_enter(&rw->rw_lock); |
| 165 | KASSERT(rw->rw_nreaders < UINT_MAX); |
| 166 | rw->rw_nreaders++; |
| 167 | mutex_spin_exit(&rw->rw_lock); |
| 168 | } |
| 169 | |
| 170 | static inline void |
| 171 | read_unlock(rwlock_t *rw) |
| 172 | { |
| 173 | |
| 174 | mutex_spin_enter(&rw->rw_lock); |
| 175 | KASSERT(0 < rw->rw_nreaders); |
| 176 | rw->rw_nreaders--; |
| 177 | mutex_spin_exit(&rw->rw_lock); |
| 178 | } |
| 179 | |
| 180 | #endif /* _LINUX_SPINLOCK_H_ */ |
| 181 | |