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);
  58 void _spin_lock_shared_contested(struct spinlock *spin, const char *ident);
  59 void _spin_pool_lock(void *chan, const char *ident);
  60 void _spin_pool_unlock(void *chan);
  61
  62 #define spin_lock(spin)                 _spin_lock(spin, __func__)
  63 #define spin_lock_quick(spin)           _spin_lock_quick(spin, __func__)
  64 #define spin_lock_shared(spin)          _spin_lock_shared(spin, __func__)
  65 #define spin_lock_shared_quick(spin)    _spin_lock_shared_quick(spin, __func__)
  66 #define spin_pool_lock(chan)            _spin_pool_lock(chan, __func__)
  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 /*
  98  * Return TRUE if the spinlock is held (we can't tell by whom, though)
  99  */
 100 static __inline int
 101 spin_held(struct spinlock *spin)
 102 {
 103         return(spin->counta != 0);
 104 }
 105
 106 /*
 107  * Obtain an exclusive spinlock and return.
 108  */
 109 static __inline void
 110 _spin_lock_quick(globaldata_t gd, struct spinlock *spin, const char *ident)
 111 {
 112         ++gd->gd_curthread->td_critcount;
 113         cpu_ccfence();
 114         ++gd->gd_spinlocks;
 115         atomic_add_int(&spin->counta, 1);
 116         if (spin->counta != 1)
 117                 _spin_lock_contested(spin, ident);
 118 #ifdef DEBUG_LOCKS
 119         int i;
 120         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 121                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
 122                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 123                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 124                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 125                                 __builtin_return_address(0);
 126                         break;
 127                 }
 128         }
 129 #endif
 130 }
 131
 132 static __inline void
 133 _spin_lock(struct spinlock *spin, const char *ident)
 134 {
 135         _spin_lock_quick(mycpu, spin, ident);
 136 }
 137
 138 /*
 139  * Release an exclusive spinlock.  We can just do this passively, only
 140  * ensuring that our spinlock count is left intact until the mutex is
 141  * cleared.
 142  */
 143 static __inline void
 144 spin_unlock_quick(globaldata_t gd, struct spinlock *spin)
 145 {
 146 #ifdef DEBUG_LOCKS
 147         int i;
 148         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 149                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 150                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 151                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 152                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 153                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 154                         break;
 155                 }
 156         }
 157 #endif
 158         /*
 159          * Don't use a locked instruction here.  To reduce latency we avoid
 160          * reading spin->counta prior to writing to it.
 161          */
 162 #ifdef DEBUG_LOCKS
 163         KKASSERT(spin->counta != 0);
 164 #endif
 165         cpu_sfence();
 166         atomic_add_int(&spin->counta, -1);
 167         cpu_sfence();
 168 #ifdef DEBUG_LOCKS
 169         KKASSERT(gd->gd_spinlocks > 0);
 170 #endif
 171         --gd->gd_spinlocks;
 172         cpu_ccfence();
 173         --gd->gd_curthread->td_critcount;
 174 }
 175
 176 static __inline void
 177 spin_unlock(struct spinlock *spin)
 178 {
 179         spin_unlock_quick(mycpu, spin);
 180 }
 181
 182 /*
 183  * Shared spinlocks
 184  */
 185 static __inline void
 186 _spin_lock_shared_quick(globaldata_t gd, struct spinlock *spin,
 187                         const char *ident)
 188 {
 189         ++gd->gd_curthread->td_critcount;
 190         cpu_ccfence();
 191         ++gd->gd_spinlocks;
 192         if (atomic_cmpset_int(&spin->counta, 0, SPINLOCK_SHARED | 1) == 0)
 193                 _spin_lock_shared_contested(spin, ident);
 194 #ifdef DEBUG_LOCKS
 195         int i;
 196         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 197                 if (gd->gd_curthread->td_spinlock_stack_id[i] == 0) {
 198                         gd->gd_curthread->td_spinlock_stack_id[i] = 1;
 199                         gd->gd_curthread->td_spinlock_stack[i] = spin;
 200                         gd->gd_curthread->td_spinlock_caller_pc[i] =
 201                                 __builtin_return_address(0);
 202                         break;
 203                 }
 204         }
 205 #endif
 206 }
 207
 208 static __inline void
 209 spin_unlock_shared_quick(globaldata_t gd, struct spinlock *spin)
 210 {
 211 #ifdef DEBUG_LOCKS
 212         int i;
 213         for (i = 0; i < SPINLOCK_DEBUG_ARRAY_SIZE; i++) {
 214                 if ((gd->gd_curthread->td_spinlock_stack_id[i] == 1) &&
 215                     (gd->gd_curthread->td_spinlock_stack[i] == spin)) {
 216                         gd->gd_curthread->td_spinlock_stack_id[i] = 0;
 217                         gd->gd_curthread->td_spinlock_stack[i] = NULL;
 218                         gd->gd_curthread->td_spinlock_caller_pc[i] = NULL;
 219                         break;
 220                 }
 221         }
 222 #endif
 223 #ifdef DEBUG_LOCKS
 224         KKASSERT(spin->counta != 0);
 225 #endif
 226         cpu_sfence();
 227         atomic_add_int(&spin->counta, -1);
 228
 229         /*
 230          * Make sure SPINLOCK_SHARED is cleared.  If another cpu tries to
 231          * get a shared or exclusive lock this loop will break out.  We're
 232          * only talking about a very trivial edge case here.
 233          */
 234         while (spin->counta == SPINLOCK_SHARED) {
 235                 if (atomic_cmpset_int(&spin->counta, SPINLOCK_SHARED, 0))
 236                         break;
 237         }
 238         cpu_sfence();
 239 #ifdef DEBUG_LOCKS
 240         KKASSERT(gd->gd_spinlocks > 0);
 241 #endif
 242         --gd->gd_spinlocks;
 243         cpu_ccfence();
 244         --gd->gd_curthread->td_critcount;
 245 }
 246
 247 static __inline void
 248 _spin_lock_shared(struct spinlock *spin, const char *ident)
 249 {
 250         _spin_lock_shared_quick(mycpu, spin, ident);
 251 }
 252
 253 static __inline void
 254 spin_unlock_shared(struct spinlock *spin)
 255 {
 256         spin_unlock_shared_quick(mycpu, spin);
 257 }
 258
 259 static __inline void
 260 spin_pool_unlock(void *chan)
 261 {
 262         _spin_pool_unlock(chan);
 263 }
 264
 265 static __inline void
 266 spin_init(struct spinlock *spin, const char *descr)
 267 {
 268         spin->counta = 0;
 269         spin->countb = 0;
 270         spin->descr  = descr;
 271 }
 272
 273 static __inline void
 274 spin_uninit(struct spinlock *spin)
 275 {
 276         /* unused */
 277 }
 278
 279 #endif  /* _KERNEL */
 280 #endif  /* _SYS_SPINLOCK2_H_ */
 281