sys/sys/spinlock2.h

   1 /*
   2  * Copyright (c) 2005 Jeffrey M. Hsu.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Jeffrey M. Hsu.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of The DragonFly Project nor the names of its
  16  *    contributors may be used to endorse or promote products derived
  17  *    from this software without specific, prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  22  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  23  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  24  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  25  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  27  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef _SYS_SPINLOCK2_H_
  34 #define _SYS_SPINLOCK2_H_
  35
  36 #ifndef _KERNEL
  37
  38 #error "This file should not be included by userland programs."
  39
  40 #else
  41
  42 #ifndef _SYS_SYSTM_H_
  43 #include <sys/systm.h>
  44 #endif
  45 #ifndef _SYS_THREAD2_H_
  46 #include <sys/thread2.h>
  47 #endif
  48 #ifndef _SYS_GLOBALDATA_H_
  49 #include <sys/globaldata.h>
  50 #endif
  51 #include <machine/atomic.h>
  52 #include <machine/cpufunc.h>
  53
  54 extern struct spinlock pmap_spin;
  55
  56 int spin_trylock_contested(struct spinlock *spin);
  57 void spin_lock_contested(struct spinlock *spin);
  58 void spin_lock_shared_contested(struct spinlock *spin);
  59 void _spin_pool_lock(void *chan);
  60 void _spin_pool_unlock(void *chan);
  61
  62 /*
  63  * Attempt to obtain an exclusive spinlock.  Returns FALSE on failure,
  64  * TRUE on success.
  65  */
  66 static __inline boolean_t
  67 spin_trylock(struct spinlock *spin)
  68 {
  69         globaldata_t gd = mycpu;
  70
  71         ++gd->gd_curthread->td_critcount;
  72         cpu_ccfence();
  73         ++gd->gd_spinlocks;
  74         if (atomic_cmpset_int(&spin->counta, 0, 1) == 0)
  75                 return (spin_trylock_contested(spin));
  76 #ifdef DEBUG_LOCKS
  77         int i;
  78         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
  79                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
  80                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
  81                         gd->gd_curthread->td_spinlock_stack[i] = spin;
  82                         gd->gd_curthread->td_spinlock_caller_pc[i] =
  83                                 __builtin_return_address(0);
  84                         break;
  85                 }
  86         }
  87 #endif
  88         return (TRUE);
  89 }
  90
  91 /*
  92  * Return TRUE if the spinlock is held (we can't tell by whom, though)
  93  */
  94 static __inline int
  95 spin_held(struct spinlock *spin)
  96 {
  97         return(spin->counta != 0);
  98 }
  99
 100 /*
 101  * Obtain an exclusive spinlock and return.
 102  */
 103 static __inline void
 104 spin_lock_quick(globaldata_t gd, struct spinlock *spin)
 105 {
 106         ++gd->gd_curthread->td_critcount;
 107         cpu_ccfence();
 108         ++gd->gd_spinlocks;
 109         atomic_add_int(&spin->counta, 1);
 110         if (spin->counta != 1)
 111                 spin_lock_contested(spin);
 112 #ifdef DEBUG_LOCKS
 113         int i;
 114         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 115                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
 116                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 117                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 118                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 119                                 __builtin_return_address(0);
 120                         break;
 121                 }
 122         }
 123 #endif
 124 }
 125
 126 static __inline void
 127 spin_lock(struct spinlock *spin)
 128 {
 129         spin_lock_quick(mycpu, spin);
 130 }
 131
 132 /*
 133  * Release an exclusive spinlock.  We can just do this passively, only
 134  * ensuring that our spinlock count is left intact until the mutex is
 135  * cleared.
 136  */
 137 static __inline void
 138 spin_unlock_quick(globaldata_t gd, struct spinlock *spin)
 139 {
 140 #ifdef DEBUG_LOCKS
 141         int i;
 142         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 143                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 144                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 145                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 146                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 147                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 148                         break;
 149                 }
 150         }
 151 #endif
 152         /*
 153          * Don't use a locked instruction here.  To reduce latency we avoid
 154          * reading spin->counta prior to writing to it.
 155          */
 156 #ifdef DEBUG_LOCKS
 157         KKASSERT(spin->counta != 0);
 158 #endif
 159         cpu_sfence();
 160         atomic_add_int(&spin->counta, -1);
 161         cpu_sfence();
 162 #ifdef DEBUG_LOCKS
 163         KKASSERT(gd->gd_spinlocks > 0);
 164 #endif
 165         --gd->gd_spinlocks;
 166         cpu_ccfence();
 167         --gd->gd_curthread->td_critcount;
 168 }
 169
 170 static __inline void
 171 spin_unlock(struct spinlock *spin)
 172 {
 173         spin_unlock_quick(mycpu, spin);
 174 }
 175
 176 /*
 177  * Shared spinlocks
 178  */
 179 static __inline void
 180 spin_lock_shared_quick(globaldata_t gd, struct spinlock *spin)
 181 {
 182         ++gd->gd_curthread->td_critcount;
 183         cpu_ccfence();
 184         ++gd->gd_spinlocks;
 185         atomic_add_int(&spin->counta, 1);
 186         if (spin->counta == 1)
 187                 atomic_set_int(&spin->counta, SPINLOCK_SHARED);
 188         if ((spin->counta & SPINLOCK_SHARED) == 0)
 189                 spin_lock_shared_contested(spin);
 190 #ifdef DEBUG_LOCKS
 191         int i;
 192         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 193                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
 194                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 195                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 196                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 197                                 __builtin_return_address(0);
 198                         break;
 199                 }
 200         }
 201 #endif
 202 }
 203
 204 static __inline void
 205 spin_unlock_shared_quick(globaldata_t gd, struct spinlock *spin)
 206 {
 207 #ifdef DEBUG_LOCKS
 208         int i;
 209         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 210                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 211                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 212                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 213                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 214                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 215                         break;
 216                 }
 217         }
 218 #endif
 219 #ifdef DEBUG_LOCKS
 220         KKASSERT(spin->counta != 0);
 221 #endif
 222         cpu_sfence();
 223         atomic_add_int(&spin->counta, -1);
 224
 225         /*
 226          * Make sure SPINLOCK_SHARED is cleared.  If another cpu tries to
 227          * get a shared or exclusive lock this loop will break out.  We're
 228          * only talking about a very trivial edge case here.
 229          */
 230         while (spin->counta == SPINLOCK_SHARED) {
 231                 if (atomic_cmpset_int(&spin->counta, SPINLOCK_SHARED, 0))
 232                         break;
 233         }
 234         cpu_sfence();
 235 #ifdef DEBUG_LOCKS
 236         KKASSERT(gd->gd_spinlocks > 0);
 237 #endif
 238         --gd->gd_spinlocks;
 239         cpu_ccfence();
 240         --gd->gd_curthread->td_critcount;
 241 }
 242
 243 static __inline void
 244 spin_lock_shared(struct spinlock *spin)
 245 {
 246         spin_lock_shared_quick(mycpu, spin);
 247 }
 248
 249 static __inline void
 250 spin_unlock_shared(struct spinlock *spin)
 251 {
 252         spin_unlock_shared_quick(mycpu, spin);
 253 }
 254
 255 static __inline void
 256 spin_pool_lock(void *chan)
 257 {
 258         _spin_pool_lock(chan);
 259 }
 260
 261 static __inline void
 262 spin_pool_unlock(void *chan)
 263 {
 264         _spin_pool_unlock(chan);
 265 }
 266
 267 static __inline void
 268 spin_init(struct spinlock *spin)
 269 {
 270         spin->counta = 0;
 271         spin->countb = 0;
 272 }
 273
 274 static __inline void
 275 spin_uninit(struct spinlock *spin)
 276 {
 277         /* unused */
 278 }
 279
 280 #endif  /* _KERNEL */
 281 #endif  /* _SYS_SPINLOCK2_H_ */
 282