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, const char *ident, int count);
  58 void _spin_lock_shared_contested(struct spinlock *spin, const char *ident,
  59                         int count);
  60 void _spin_pool_lock(void *chan, const char *ident);
  61 void _spin_pool_unlock(void *chan);
  62
  63 #define spin_lock(spin)                 _spin_lock(spin, __func__)
  64 #define spin_lock_quick(spin)           _spin_lock_quick(spin, __func__)
  65 #define spin_lock_shared(spin)          _spin_lock_shared(spin, __func__)
  66 #define spin_lock_shared_quick(spin)    _spin_lock_shared_quick(spin, __func__)
  67 #define spin_pool_lock(chan)            _spin_pool_lock(chan, __func__)
  68
  69 /*
  70  * Attempt to obtain an exclusive spinlock.  Returns FALSE on failure,
  71  * TRUE on success.
  72  */
  73 static __inline boolean_t
  74 spin_trylock(struct spinlock *spin)
  75 {
  76         globaldata_t gd = mycpu;
  77
  78         ++gd->gd_curthread->td_critcount;
  79         cpu_ccfence();
  80         ++gd->gd_spinlocks;
  81         if (atomic_cmpset_int(&spin->counta, 0, 1) == 0)
  82                 return (spin_trylock_contested(spin));
  83 #ifdef DEBUG_LOCKS
  84         int i;
  85         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
  86                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
  87                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
  88                         gd->gd_curthread->td_spinlock_stack[i] = spin;
  89                         gd->gd_curthread->td_spinlock_caller_pc[i] =
  90                                 __builtin_return_address(0);
  91                         break;
  92                 }
  93         }
  94 #endif
  95         return (TRUE);
  96 }
  97
  98 /*
  99  * Return TRUE if the spinlock is held (we can't tell by whom, though)
 100  */
 101 static __inline int
 102 spin_held(struct spinlock *spin)
 103 {
 104         return((spin->counta & ~SPINLOCK_SHARED) != 0);
 105 }
 106
 107 /*
 108  * Obtain an exclusive spinlock and return.  It is possible for the
 109  * SPINLOCK_SHARED bit to already be set, in which case the contested
 110  * code is called to fix it up.
 111  */
 112 static __inline void
 113 _spin_lock_quick(globaldata_t gd, struct spinlock *spin, const char *ident)
 114 {
 115         int count;
 116
 117         ++gd->gd_curthread->td_critcount;
 118         cpu_ccfence();
 119         ++gd->gd_spinlocks;
 120         if ((count = atomic_fetchadd_int(&spin->counta, 1)) != 0)
 121                 _spin_lock_contested(spin, ident, count + 1);
 122 #ifdef DEBUG_LOCKS
 123         int i;
 124         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 125                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
 126                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 127                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 128                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 129                                 __builtin_return_address(0);
 130                         break;
 131                 }
 132         }
 133 #endif
 134 }
 135
 136 static __inline void
 137 _spin_lock(struct spinlock *spin, const char *ident)
 138 {
 139         _spin_lock_quick(mycpu, spin, ident);
 140 }
 141
 142 /*
 143  * Release an exclusive spinlock.  We can just do this passively, only
 144  * ensuring that our spinlock count is left intact until the mutex is
 145  * cleared.
 146  */
 147 static __inline void
 148 spin_unlock_quick(globaldata_t gd, struct spinlock *spin)
 149 {
 150 #ifdef DEBUG_LOCKS
 151         int i;
 152         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 153                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 154                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 155                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 156                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 157                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 158                         break;
 159                 }
 160         }
 161 #endif
 162         /*
 163          * Don't use a locked instruction here.  To reduce latency we avoid
 164          * reading spin->counta prior to writing to it.
 165          */
 166 #ifdef DEBUG_LOCKS
 167         KKASSERT(spin->counta != 0);
 168 #endif
 169         cpu_sfence();
 170         atomic_add_int(&spin->counta, -1);
 171         cpu_sfence();
 172 #ifdef DEBUG_LOCKS
 173         KKASSERT(gd->gd_spinlocks > 0);
 174 #endif
 175         --gd->gd_spinlocks;
 176         cpu_ccfence();
 177         --gd->gd_curthread->td_critcount;
 178 }
 179
 180 static __inline void
 181 spin_unlock(struct spinlock *spin)
 182 {
 183         spin_unlock_quick(mycpu, spin);
 184 }
 185
 186 /*
 187  * Shared spinlock.  Acquire a count, if SPINLOCK_SHARED is not already
 188  * set then set it.  The bit will already be set in the unmixed critical
 189  * path.
 190  */
 191 static __inline void
 192 _spin_lock_shared_quick(globaldata_t gd, struct spinlock *spin,
 193                         const char *ident)
 194 {
 195         int counta;
 196
 197         ++gd->gd_curthread->td_critcount;
 198         cpu_ccfence();
 199         ++gd->gd_spinlocks;
 200         counta = atomic_fetchadd_int(&spin->counta, 1);
 201         if (counta == 0) {
 202                 atomic_set_int(&spin->counta, SPINLOCK_SHARED);
 203         } else if ((counta & SPINLOCK_SHARED) == 0) {
 204                 atomic_add_int(&spin->counta, -1);
 205                 _spin_lock_shared_contested(spin, ident, counta);
 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] == 0) {
 211                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 212                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 213                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 214                                 __builtin_return_address(0);
 215                         break;
 216                 }
 217         }
 218 #endif
 219 }
 220
 221 /*
 222  * Unlock a shared lock.  For convenience we allow the last transition
 223  * to be to (SPINLOCK_SHARED|0), leaving the SPINLOCK_SHARED bit set
 224  * with a count to 0 which will optimize the next shared lock obtained.
 225  */
 226 static __inline void
 227 spin_unlock_shared_quick(globaldata_t gd, struct spinlock *spin)
 228 {
 229 #ifdef DEBUG_LOCKS
 230         int i;
 231         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 232                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 233                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 234                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 235                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 236                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 237                         break;
 238                 }
 239         }
 240 #endif
 241 #ifdef DEBUG_LOCKS
 242         KKASSERT(spin->counta != 0);
 243 #endif
 244         cpu_sfence();
 245         atomic_add_int(&spin->counta, -1);
 246
 247 #ifdef DEBUG_LOCKS
 248         KKASSERT(gd->gd_spinlocks > 0);
 249 #endif
 250         --gd->gd_spinlocks;
 251         cpu_ccfence();
 252         --gd->gd_curthread->td_critcount;
 253 }
 254
 255 static __inline void
 256 _spin_lock_shared(struct spinlock *spin, const char *ident)
 257 {
 258         _spin_lock_shared_quick(mycpu, spin, ident);
 259 }
 260
 261 static __inline void
 262 spin_unlock_shared(struct spinlock *spin)
 263 {
 264         spin_unlock_shared_quick(mycpu, spin);
 265 }
 266
 267 static __inline void
 268 spin_pool_unlock(void *chan)
 269 {
 270         _spin_pool_unlock(chan);
 271 }
 272
 273 static __inline void
 274 spin_init(struct spinlock *spin, const char *descr)
 275 {
 276         spin->counta = 0;
 277         spin->countb = 0;
 278         spin->descr  = descr;
 279 }
 280
 281 static __inline void
 282 spin_uninit(struct spinlock *spin)
 283 {
 284         /* unused */
 285 }
 286
 287 #endif  /* _KERNEL */
 288 #endif  /* _SYS_SPINLOCK2_H_ */
 289