lib/spinlock_debug.c

   1 /*
   2  * Copyright 2005, Red Hat, Inc., Ingo Molnar
   3  * Released under the General Public License (GPL).
   4  *
   5  * This file contains the spinlock/rwlock implementations for
   6  * DEBUG_SPINLOCK.
   7  */
   8
   9 #include <linux/spinlock.h>
  10 #include <linux/nmi.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/debug_locks.h>
  13 #include <linux/delay.h>
  14 #include <linux/module.h>
  15
  16 void __spin_lock_init(spinlock_t *lock, const char *name,
  17                       struct lock_class_key *key)
  18 {
  19 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  20         /*
  21          * Make sure we are not reinitializing a held lock:
  22          */
  23         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  24         lockdep_init_map(&lock->dep_map, name, key, 0);
  25 #endif
  26         lock->raw_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
  27         lock->magic = SPINLOCK_MAGIC;
  28         lock->owner = SPINLOCK_OWNER_INIT;
  29         lock->owner_cpu = -1;
  30 }
  31
  32 EXPORT_SYMBOL(__spin_lock_init);
  33
  34 void __rwlock_init(rwlock_t *lock, const char *name,
  35                    struct lock_class_key *key)
  36 {
  37 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  38         /*
  39          * Make sure we are not reinitializing a held lock:
  40          */
  41         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  42         lockdep_init_map(&lock->dep_map, name, key, 0);
  43 #endif
  44         lock->raw_lock = (raw_rwlock_t) __RAW_RW_LOCK_UNLOCKED;
  45         lock->magic = RWLOCK_MAGIC;
  46         lock->owner = SPINLOCK_OWNER_INIT;
  47         lock->owner_cpu = -1;
  48 }
  49
  50 EXPORT_SYMBOL(__rwlock_init);
  51
  52 static void spin_bug(spinlock_t *lock, const char *msg)
  53 {
  54         struct task_struct *owner = NULL;
  55
  56         if (!debug_locks_off())
  57                 return;
  58
  59         if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
  60                 owner = lock->owner;
  61         printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
  62                 msg, raw_smp_processor_id(),
  63                 current->comm, current->pid);
  64         printk(KERN_EMERG " lock: %p, .magic: %08x, .owner: %s/%d, "
  65                         ".owner_cpu: %d\n",
  66                 lock, lock->magic,
  67                 owner ? owner->comm : "<none>",
  68                 owner ? owner->pid : -1,
  69                 lock->owner_cpu);
  70         dump_stack();
  71 }
  72
  73 #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
  74
  75 static inline void
  76 debug_spin_lock_before(spinlock_t *lock)
  77 {
  78         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  79         SPIN_BUG_ON(lock->owner == current, lock, "recursion");
  80         SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
  81                                                         lock, "cpu recursion");
  82 }
  83
  84 static inline void debug_spin_lock_after(spinlock_t *lock)
  85 {
  86         lock->owner_cpu = raw_smp_processor_id();
  87         lock->owner = current;
  88 }
  89
  90 static inline void debug_spin_unlock(spinlock_t *lock)
  91 {
  92         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  93         SPIN_BUG_ON(!spin_is_locked(lock), lock, "already unlocked");
  94         SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
  95         SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
  96                                                         lock, "wrong CPU");
  97         lock->owner = SPINLOCK_OWNER_INIT;
  98         lock->owner_cpu = -1;
  99 }
 100
 101 static void __spin_lock_debug(spinlock_t *lock)
 102 {
 103         u64 i;
 104         u64 loops = loops_per_jiffy * HZ;
 105         int print_once = 1;
 106
 107         for (;;) {
 108                 for (i = 0; i < loops; i++) {
 109                         if (__raw_spin_trylock(&lock->raw_lock))
 110                                 return;
 111                         __delay(1);
 112                 }
 113                 /* lockup suspected: */
 114                 if (print_once) {
 115                         print_once = 0;
 116                         printk(KERN_EMERG "BUG: spinlock lockup on CPU#%d, "
 117                                         "%s/%d, %p\n",
 118                                 raw_smp_processor_id(), current->comm,
 119                                 current->pid, lock);
 120                         dump_stack();
 121 #ifdef CONFIG_SMP
 122                         trigger_all_cpu_backtrace();
 123 #endif
 124                 }
 125         }
 126 }
 127
 128 void _raw_spin_lock(spinlock_t *lock)
 129 {
 130         debug_spin_lock_before(lock);
 131         if (unlikely(!__raw_spin_trylock(&lock->raw_lock)))
 132                 __spin_lock_debug(lock);
 133         debug_spin_lock_after(lock);
 134 }
 135
 136 int _raw_spin_trylock(spinlock_t *lock)
 137 {
 138         int ret = __raw_spin_trylock(&lock->raw_lock);
 139
 140         if (ret)
 141                 debug_spin_lock_after(lock);
 142 #ifndef CONFIG_SMP
 143         /*
 144          * Must not happen on UP:
 145          */
 146         SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 147 #endif
 148         return ret;
 149 }
 150
 151 void _raw_spin_unlock(spinlock_t *lock)
 152 {
 153         debug_spin_unlock(lock);
 154         __raw_spin_unlock(&lock->raw_lock);
 155 }
 156
 157 static void rwlock_bug(rwlock_t *lock, const char *msg)
 158 {
 159         if (!debug_locks_off())
 160                 return;
 161
 162         printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 163                 msg, raw_smp_processor_id(), current->comm,
 164                 current->pid, lock);
 165         dump_stack();
 166 }
 167
 168 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 169
 170 #if 0           /* __write_lock_debug() can lock up - maybe this can too? */
 171 static void __read_lock_debug(rwlock_t *lock)
 172 {
 173         u64 i;
 174         u64 loops = loops_per_jiffy * HZ;
 175         int print_once = 1;
 176
 177         for (;;) {
 178                 for (i = 0; i < loops; i++) {
 179                         if (__raw_read_trylock(&lock->raw_lock))
 180                                 return;
 181                         __delay(1);
 182                 }
 183                 /* lockup suspected: */
 184                 if (print_once) {
 185                         print_once = 0;
 186                         printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
 187                                         "%s/%d, %p\n",
 188                                 raw_smp_processor_id(), current->comm,
 189                                 current->pid, lock);
 190                         dump_stack();
 191                 }
 192         }
 193 }
 194 #endif
 195
 196 void _raw_read_lock(rwlock_t *lock)
 197 {
 198         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 199         __raw_read_lock(&lock->raw_lock);
 200 }
 201
 202 int _raw_read_trylock(rwlock_t *lock)
 203 {
 204         int ret = __raw_read_trylock(&lock->raw_lock);
 205
 206 #ifndef CONFIG_SMP
 207         /*
 208          * Must not happen on UP:
 209          */
 210         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 211 #endif
 212         return ret;
 213 }
 214
 215 void _raw_read_unlock(rwlock_t *lock)
 216 {
 217         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 218         __raw_read_unlock(&lock->raw_lock);
 219 }
 220
 221 static inline void debug_write_lock_before(rwlock_t *lock)
 222 {
 223         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 224         RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 225         RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 226                                                         lock, "cpu recursion");
 227 }
 228
 229 static inline void debug_write_lock_after(rwlock_t *lock)
 230 {
 231         lock->owner_cpu = raw_smp_processor_id();
 232         lock->owner = current;
 233 }
 234
 235 static inline void debug_write_unlock(rwlock_t *lock)
 236 {
 237         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 238         RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 239         RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 240                                                         lock, "wrong CPU");
 241         lock->owner = SPINLOCK_OWNER_INIT;
 242         lock->owner_cpu = -1;
 243 }
 244
 245 #if 0           /* This can cause lockups */
 246 static void __write_lock_debug(rwlock_t *lock)
 247 {
 248         u64 i;
 249         u64 loops = loops_per_jiffy * HZ;
 250         int print_once = 1;
 251
 252         for (;;) {
 253                 for (i = 0; i < loops; i++) {
 254                         if (__raw_write_trylock(&lock->raw_lock))
 255                                 return;
 256                         __delay(1);
 257                 }
 258                 /* lockup suspected: */
 259                 if (print_once) {
 260                         print_once = 0;
 261                         printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
 262                                         "%s/%d, %p\n",
 263                                 raw_smp_processor_id(), current->comm,
 264                                 current->pid, lock);
 265                         dump_stack();
 266                 }
 267         }
 268 }
 269 #endif
 270
 271 void _raw_write_lock(rwlock_t *lock)
 272 {
 273         debug_write_lock_before(lock);
 274         __raw_write_lock(&lock->raw_lock);
 275         debug_write_lock_after(lock);
 276 }
 277
 278 int _raw_write_trylock(rwlock_t *lock)
 279 {
 280         int ret = __raw_write_trylock(&lock->raw_lock);
 281
 282         if (ret)
 283                 debug_write_lock_after(lock);
 284 #ifndef CONFIG_SMP
 285         /*
 286          * Must not happen on UP:
 287          */
 288         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 289 #endif
 290         return ret;
 291 }
 292
 293 void _raw_write_unlock(rwlock_t *lock)
 294 {
 295         debug_write_unlock(lock);
 296         __raw_write_unlock(&lock->raw_lock);
 297 }