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 #ifdef SMP
  57
  58 int spin_trylock_contested(struct spinlock *spin);
  59 void spin_lock_contested(struct spinlock *spin);
  60 void spin_lock_shared_contested(struct spinlock *spin);
  61 void _spin_pool_lock(void *chan);
  62 void _spin_pool_unlock(void *chan);
  63
  64 #endif
  65
  66 #ifdef SMP
  67
  68 /*
  69  * Attempt to obtain an exclusive spinlock.  Returns FALSE on failure,
  70  * TRUE on success.
  71  */
  72 static __inline boolean_t
  73 spin_trylock(struct spinlock *spin)
  74 {
  75         globaldata_t gd = mycpu;
  76
  77         ++gd->gd_curthread->td_critcount;
  78         cpu_ccfence();
  79         ++gd->gd_spinlocks;
  80         if (atomic_cmpset_int(&spin->counta, 0, 1) == 0)
  81                 return (spin_trylock_contested(spin));
  82 #ifdef DEBUG_LOCKS
  83         int i;
  84         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
  85                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
  86                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
  87                         gd->gd_curthread->td_spinlock_stack[i] = spin;
  88                         gd->gd_curthread->td_spinlock_caller_pc[i] =
  89                                 __builtin_return_address(0);
  90                         break;
  91                 }
  92         }
  93 #endif
  94         return (TRUE);
  95 }
  96
  97 #else
  98
  99 static __inline boolean_t
 100 spin_trylock(struct spinlock *spin)
 101 {
 102         globaldata_t gd = mycpu;
 103
 104         ++gd->gd_curthread->td_critcount;
 105         cpu_ccfence();
 106         ++gd->gd_spinlocks;
 107         return (TRUE);
 108 }
 109
 110 #endif
 111
 112 /*
 113  * Return TRUE if the spinlock is held (we can't tell by whom, though)
 114  */
 115 static __inline int
 116 spin_held(struct spinlock *spin)
 117 {
 118         return(spin->counta != 0);
 119 }
 120
 121 /*
 122  * Obtain an exclusive spinlock and return.
 123  */
 124 static __inline void
 125 spin_lock_quick(globaldata_t gd, struct spinlock *spin)
 126 {
 127         ++gd->gd_curthread->td_critcount;
 128         cpu_ccfence();
 129         ++gd->gd_spinlocks;
 130 #ifdef SMP
 131         atomic_add_int(&spin->counta, 1);
 132         if (spin->counta != 1)
 133                 spin_lock_contested(spin);
 134 #ifdef DEBUG_LOCKS
 135         int i;
 136         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 137                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
 138                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 139                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 140                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 141                                 __builtin_return_address(0);
 142                         break;
 143                 }
 144         }
 145 #endif
 146 #endif
 147 }
 148
 149 static __inline void
 150 spin_lock(struct spinlock *spin)
 151 {
 152         spin_lock_quick(mycpu, spin);
 153 }
 154
 155 /*
 156  * Release an exclusive spinlock.  We can just do this passively, only
 157  * ensuring that our spinlock count is left intact until the mutex is
 158  * cleared.
 159  */
 160 static __inline void
 161 spin_unlock_quick(globaldata_t gd, struct spinlock *spin)
 162 {
 163 #ifdef SMP
 164 #ifdef DEBUG_LOCKS
 165         int i;
 166         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 167                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 168                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 169                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 170                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 171                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 172                         break;
 173                 }
 174         }
 175 #endif
 176         /*
 177          * Don't use a locked instruction here.  To reduce latency we avoid
 178          * reading spin->counta prior to writing to it.
 179          */
 180 #ifdef DEBUG_LOCKS
 181         KKASSERT(spin->counta != 0);
 182 #endif
 183         cpu_sfence();
 184         atomic_add_int(&spin->counta, -1);
 185         cpu_sfence();
 186 #endif
 187 #ifdef DEBUG_LOCKS
 188         KKASSERT(gd->gd_spinlocks > 0);
 189 #endif
 190         --gd->gd_spinlocks;
 191         cpu_ccfence();
 192         --gd->gd_curthread->td_critcount;
 193 }
 194
 195 static __inline void
 196 spin_unlock(struct spinlock *spin)
 197 {
 198         spin_unlock_quick(mycpu, spin);
 199 }
 200
 201 /*
 202  * Shared spinlocks
 203  */
 204 static __inline void
 205 spin_lock_shared_quick(globaldata_t gd, struct spinlock *spin)
 206 {
 207         ++gd->gd_curthread->td_critcount;
 208         cpu_ccfence();
 209         ++gd->gd_spinlocks;
 210 #ifdef SMP
 211         atomic_add_int(&spin->counta, 1);
 212         if (spin->counta == 1)
 213                 atomic_set_int(&spin->counta, SPINLOCK_SHARED);
 214         if ((spin->counta & SPINLOCK_SHARED) == 0)
 215                 spin_lock_shared_contested(spin);
 216 #ifdef DEBUG_LOCKS
 217         int i;
 218         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 219                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
 220                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 221                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 222                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 223                                 __builtin_return_address(0);
 224                         break;
 225                 }
 226         }
 227 #endif
 228 #endif
 229 }
 230
 231 static __inline void
 232 spin_unlock_shared_quick(globaldata_t gd, struct spinlock *spin)
 233 {
 234 #ifdef SMP
 235 #ifdef DEBUG_LOCKS
 236         int i;
 237         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 238                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 239                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 240                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 241                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 242                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 243                         break;
 244                 }
 245         }
 246 #endif
 247 #ifdef DEBUG_LOCKS
 248         KKASSERT(spin->counta != 0);
 249 #endif
 250         cpu_sfence();
 251         atomic_add_int(&spin->counta, -1);
 252
 253         /*
 254          * Make sure SPINLOCK_SHARED is cleared.  If another cpu tries to
 255          * get a shared or exclusive lock this loop will break out.  We're
 256          * only talking about a very trivial edge case here.
 257          */
 258         while (spin->counta == SPINLOCK_SHARED) {
 259                 if (atomic_cmpset_int(&spin->counta, SPINLOCK_SHARED, 0))
 260                         break;
 261         }
 262         cpu_sfence();
 263 #endif
 264 #ifdef DEBUG_LOCKS
 265         KKASSERT(gd->gd_spinlocks > 0);
 266 #endif
 267         --gd->gd_spinlocks;
 268         cpu_ccfence();
 269         --gd->gd_curthread->td_critcount;
 270 }
 271
 272 static __inline void
 273 spin_lock_shared(struct spinlock *spin)
 274 {
 275         spin_lock_shared_quick(mycpu, spin);
 276 }
 277
 278 static __inline void
 279 spin_unlock_shared(struct spinlock *spin)
 280 {
 281         spin_unlock_shared_quick(mycpu, spin);
 282 }
 283
 284 static __inline void
 285 spin_pool_lock(void *chan)
 286 {
 287 #ifdef SMP
 288         _spin_pool_lock(chan);
 289 #else
 290         spin_lock(NULL);
 291 #endif
 292 }
 293
 294 static __inline void
 295 spin_pool_unlock(void *chan)
 296 {
 297 #ifdef SMP
 298         _spin_pool_unlock(chan);
 299 #else
 300         spin_unlock(NULL);
 301 #endif
 302 }
 303
 304 static __inline void
 305 spin_init(struct spinlock *spin)
 306 {
 307         spin->counta = 0;
 308         spin->countb = 0;
 309 }
 310
 311 static __inline void
 312 spin_uninit(struct spinlock *spin)
 313 {
 314         /* unused */
 315 }
 316
 317 #endif  /* _KERNEL */
 318 #endif  /* _SYS_SPINLOCK2_H_ */
 319