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