| 1 | /* $NetBSD: mutex.h,v 1.20 2010/02/08 09:54:27 skrll Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2002, 2006, 2007, 2008, 2009 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 _SYS_MUTEX_H_ |
| 33 | #define _SYS_MUTEX_H_ |
| 34 | |
| 35 | /* |
| 36 | * There are 2 types of mutexes: |
| 37 | * |
| 38 | * * Adaptive -- If the lock is already held, the thread attempting |
| 39 | * to acquire the lock determines if the thread that holds it is |
| 40 | * currently running. If so, it spins, else it sleeps. |
| 41 | * |
| 42 | * * Spin -- If the lock is already held, the thread attempting to |
| 43 | * acquire the lock spins. The IPL will be raised on entry. |
| 44 | * |
| 45 | * Machine dependent code must provide the following: |
| 46 | * |
| 47 | * struct mutex |
| 48 | * The actual mutex structure. This structure is mostly |
| 49 | * opaque to machine-independent code; most access are done |
| 50 | * through macros. However, machine-independent code must |
| 51 | * be able to access the following members: |
| 52 | * |
| 53 | * uintptr_t mtx_owner |
| 54 | * ipl_cookie_t mtx_ipl |
| 55 | * __cpu_simple_lock_t mtx_lock |
| 56 | * |
| 57 | * If an architecture can be considered 'simple' (no interlock required in |
| 58 | * the MP case, or no MP) it need only define __HAVE_SIMPLE_MUTEXES and |
| 59 | * provide the following: |
| 60 | * |
| 61 | * struct mutex |
| 62 | * |
| 63 | * [additionally:] |
| 64 | * volatile integer mtx_id |
| 65 | * |
| 66 | * MUTEX_RECEIVE(mtx) |
| 67 | * Post a load fence after acquiring the mutex, if necessary. |
| 68 | * |
| 69 | * MUTEX_GIVE(mtx) |
| 70 | * Post a load/store fence after releasing the mutex, if |
| 71 | * necessary. |
| 72 | * |
| 73 | * MUTEX_CAS(ptr, old, new) |
| 74 | * Perform an atomic "compare and swap" operation and |
| 75 | * evaluate to true or false according to the success |
| 76 | * |
| 77 | * Otherwise, the following must be defined: |
| 78 | * |
| 79 | * MUTEX_INITIALIZE_SPIN(mtx, dodebug, minipl) |
| 80 | * Initialize a spin mutex. |
| 81 | * |
| 82 | * MUTEX_INITIALIZE_ADAPTIVE(mtx, dodebug) |
| 83 | * Initialize an adaptive mutex. |
| 84 | * |
| 85 | * MUTEX_DESTROY(mtx) |
| 86 | * Tear down a mutex. |
| 87 | * |
| 88 | * MUTEX_ADAPTIVE_P(mtx) |
| 89 | * Evaluates to true if the mutex is an adaptive mutex. |
| 90 | * |
| 91 | * MUTEX_SPIN_P(mtx) |
| 92 | * Evaluates to true if the mutex is a spin mutex. |
| 93 | * |
| 94 | * MUTEX_OWNER(owner) |
| 95 | * Returns the owner of the adaptive mutex (LWP address). |
| 96 | * |
| 97 | * MUTEX_OWNED(owner) |
| 98 | * Returns non-zero if an adaptive mutex is currently |
| 99 | * held by an LWP. |
| 100 | * |
| 101 | * MUTEX_HAS_WAITERS(mtx) |
| 102 | * Returns true if the mutex has waiters. |
| 103 | * |
| 104 | * MUTEX_SET_WAITERS(mtx) |
| 105 | * Mark the mutex has having waiters. |
| 106 | * |
| 107 | * MUTEX_ACQUIRE(mtx, owner) |
| 108 | * Try to acquire an adaptive mutex such that: |
| 109 | * if (lock held OR waiters) |
| 110 | * return 0; |
| 111 | * else |
| 112 | * return 1; |
| 113 | * Must be MP/interrupt atomic. |
| 114 | * |
| 115 | * MUTEX_RELEASE(mtx) |
| 116 | * Release the lock and clear the "has waiters" indication. |
| 117 | * Must be interrupt atomic, need not be MP safe. |
| 118 | * |
| 119 | * MUTEX_DEBUG_P(mtx) |
| 120 | * Evaluates to true if the mutex is initialized with |
| 121 | * dodebug==true. Only used in the LOCKDEBUG case. |
| 122 | * |
| 123 | * Machine dependent code may optionally provide stubs for the following |
| 124 | * functions to implement the easy (unlocked / no waiters) cases. If |
| 125 | * these stubs are provided, __HAVE_MUTEX_STUBS should be defined. |
| 126 | * |
| 127 | * mutex_enter() |
| 128 | * mutex_exit() |
| 129 | * |
| 130 | * Two additional stubs may be implemented that handle only the spinlock |
| 131 | * case, primarily for the scheduler. __HAVE_SPIN_MUTEX_STUBS should be |
| 132 | * defined if these are provided: |
| 133 | * |
| 134 | * mutex_spin_enter() |
| 135 | * mutex_spin_exit() |
| 136 | */ |
| 137 | |
| 138 | #if defined(_KERNEL_OPT) |
| 139 | #include "opt_lockdebug.h" |
| 140 | #endif |
| 141 | |
| 142 | #if !defined(_KERNEL) |
| 143 | #include <sys/types.h> |
| 144 | #include <sys/inttypes.h> |
| 145 | #endif |
| 146 | |
| 147 | typedef enum kmutex_type_t { |
| 148 | MUTEX_SPIN = 0, /* To get a spin mutex at IPL_NONE */ |
| 149 | MUTEX_ADAPTIVE = 1, /* For porting code written for Solaris */ |
| 150 | MUTEX_DEFAULT = 2, /* The only native, endorsed type */ |
| 151 | MUTEX_DRIVER = 3, /* For porting code written for Solaris */ |
| 152 | MUTEX_NODEBUG = 4 /* Disables LOCKDEBUG; use with care */ |
| 153 | } kmutex_type_t; |
| 154 | |
| 155 | typedef struct kmutex kmutex_t; |
| 156 | |
| 157 | #if defined(__MUTEX_PRIVATE) |
| 158 | |
| 159 | #define MUTEX_THREAD ((uintptr_t)-16L) |
| 160 | |
| 161 | #define MUTEX_BIT_SPIN 0x01 |
| 162 | #define MUTEX_BIT_WAITERS 0x02 |
| 163 | |
| 164 | #if defined(LOCKDEBUG) |
| 165 | #define MUTEX_BIT_NODEBUG 0x04 /* LOCKDEBUG disabled */ |
| 166 | #else |
| 167 | #define MUTEX_BIT_NODEBUG 0x00 /* do nothing */ |
| 168 | #endif /* LOCKDEBUG */ |
| 169 | |
| 170 | #define MUTEX_SPIN_IPL(mtx) ((mtx)->mtx_ipl) |
| 171 | #define MUTEX_SPIN_OLDSPL(ci) ((ci)->ci_mtx_oldspl) |
| 172 | |
| 173 | void mutex_vector_enter(kmutex_t *); |
| 174 | void mutex_vector_exit(kmutex_t *); |
| 175 | void mutex_spin_retry(kmutex_t *); |
| 176 | void mutex_wakeup(kmutex_t *); |
| 177 | |
| 178 | #endif /* __MUTEX_PRIVATE */ |
| 179 | |
| 180 | #ifdef _KERNEL |
| 181 | #include <sys/intr.h> |
| 182 | #endif |
| 183 | |
| 184 | #include <machine/mutex.h> |
| 185 | |
| 186 | /* |
| 187 | * Return true if no spin mutexes are held by the current CPU. |
| 188 | */ |
| 189 | #ifndef MUTEX_NO_SPIN_ACTIVE_P |
| 190 | #define MUTEX_NO_SPIN_ACTIVE_P(ci) ((ci)->ci_mtx_count == 0) |
| 191 | #endif |
| 192 | |
| 193 | #ifdef _KERNEL |
| 194 | |
| 195 | void mutex_init(kmutex_t *, kmutex_type_t, int); |
| 196 | void mutex_destroy(kmutex_t *); |
| 197 | |
| 198 | void mutex_enter(kmutex_t *); |
| 199 | void mutex_exit(kmutex_t *); |
| 200 | |
| 201 | void mutex_spin_enter(kmutex_t *); |
| 202 | void mutex_spin_exit(kmutex_t *); |
| 203 | |
| 204 | int mutex_tryenter(kmutex_t *); |
| 205 | |
| 206 | int mutex_owned(kmutex_t *); |
| 207 | lwp_t *mutex_owner(kmutex_t *); |
| 208 | |
| 209 | void mutex_obj_init(void); |
| 210 | kmutex_t *mutex_obj_alloc(kmutex_type_t, int); |
| 211 | void mutex_obj_hold(kmutex_t *); |
| 212 | bool mutex_obj_free(kmutex_t *); |
| 213 | |
| 214 | #endif /* _KERNEL */ |
| 215 | |
| 216 | #endif /* _SYS_MUTEX_H_ */ |
| 217 | |