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/export.h>
  15
  16 void __raw_spin_lock_init(raw_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 = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  27         lock->magic = SPINLOCK_MAGIC;
  28         lock->owner = SPINLOCK_OWNER_INIT;
  29         lock->owner_cpu = -1;
  30 }
  31
  32 EXPORT_SYMBOL(__raw_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 = (arch_rwlock_t) __ARCH_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_dump(raw_spinlock_t *lock, const char *msg)
  53 {
  54         struct task_struct *owner = NULL;
  55
  56         if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
  57                 owner = lock->owner;
  58         printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
  59                 msg, raw_smp_processor_id(),
  60                 current->comm, task_pid_nr(current));
  61         printk(KERN_EMERG " lock: %ps, .magic: %08x, .owner: %s/%d, "
  62                         ".owner_cpu: %d\n",
  63                 lock, lock->magic,
  64                 owner ? owner->comm : "<none>",
  65                 owner ? task_pid_nr(owner) : -1,
  66                 lock->owner_cpu);
  67         dump_stack();
  68 }
  69
  70 static void spin_bug(raw_spinlock_t *lock, const char *msg)
  71 {
  72         if (!debug_locks_off())
  73                 return;
  74
  75         spin_dump(lock, msg);
  76 }
  77
  78 #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
  79
  80 static inline void
  81 debug_spin_lock_before(raw_spinlock_t *lock)
  82 {
  83         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  84         SPIN_BUG_ON(lock->owner == current, lock, "recursion");
  85         SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
  86                                                         lock, "cpu recursion");
  87 }
  88
  89 static inline void debug_spin_lock_after(raw_spinlock_t *lock)
  90 {
  91         lock->owner_cpu = raw_smp_processor_id();
  92         lock->owner = current;
  93 }
  94
  95 static inline void debug_spin_unlock(raw_spinlock_t *lock)
  96 {
  97         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  98         SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
  99         SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
 100         SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 101                                                         lock, "wrong CPU");
 102         lock->owner = SPINLOCK_OWNER_INIT;
 103         lock->owner_cpu = -1;
 104 }
 105
 106 static void __spin_lock_debug(raw_spinlock_t *lock)
 107 {
 108         u64 i;
 109         u64 loops = loops_per_jiffy * HZ;
 110         int print_once = 1;
 111
 112         for (;;) {
 113                 for (i = 0; i < loops; i++) {
 114                         if (arch_spin_trylock(&lock->raw_lock))
 115                                 return;
 116                         __delay(1);
 117                 }
 118                 /* lockup suspected: */
 119                 if (print_once) {
 120                         print_once = 0;
 121                         spin_dump(lock, "lockup suspected");
 122 #ifdef CONFIG_SMP
 123                         trigger_all_cpu_backtrace();
 124 #endif
 125                 }
 126         }
 127 }
 128
 129 void do_raw_spin_lock(raw_spinlock_t *lock)
 130 {
 131         debug_spin_lock_before(lock);
 132         if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
 133                 __spin_lock_debug(lock);
 134         debug_spin_lock_after(lock);
 135 }
 136
 137 int do_raw_spin_trylock(raw_spinlock_t *lock)
 138 {
 139         int ret = arch_spin_trylock(&lock->raw_lock);
 140
 141         if (ret)
 142                 debug_spin_lock_after(lock);
 143 #ifndef CONFIG_SMP
 144         /*
 145          * Must not happen on UP:
 146          */
 147         SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 148 #endif
 149         return ret;
 150 }
 151
 152 void do_raw_spin_unlock(raw_spinlock_t *lock)
 153 {
 154         debug_spin_unlock(lock);
 155         arch_spin_unlock(&lock->raw_lock);
 156 }
 157
 158 static void rwlock_bug(rwlock_t *lock, const char *msg)
 159 {
 160         if (!debug_locks_off())
 161                 return;
 162
 163         printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 164                 msg, raw_smp_processor_id(), current->comm,
 165                 task_pid_nr(current), lock);
 166         dump_stack();
 167 }
 168
 169 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 170
 171 #if 0           /* __write_lock_debug() can lock up - maybe this can too? */
 172 static void __read_lock_debug(rwlock_t *lock)
 173 {
 174         u64 i;
 175         u64 loops = loops_per_jiffy * HZ;
 176         int print_once = 1;
 177
 178         for (;;) {
 179                 for (i = 0; i < loops; i++) {
 180                         if (arch_read_trylock(&lock->raw_lock))
 181                                 return;
 182                         __delay(1);
 183                 }
 184                 /* lockup suspected: */
 185                 if (print_once) {
 186                         print_once = 0;
 187                         printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
 188                                         "%s/%d, %p\n",
 189                                 raw_smp_processor_id(), current->comm,
 190                                 current->pid, lock);
 191                         dump_stack();
 192                 }
 193         }
 194 }
 195 #endif
 196
 197 void do_raw_read_lock(rwlock_t *lock)
 198 {
 199         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 200         arch_read_lock(&lock->raw_lock);
 201 }
 202
 203 int do_raw_read_trylock(rwlock_t *lock)
 204 {
 205         int ret = arch_read_trylock(&lock->raw_lock);
 206
 207 #ifndef CONFIG_SMP
 208         /*
 209          * Must not happen on UP:
 210          */
 211         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 212 #endif
 213         return ret;
 214 }
 215
 216 void do_raw_read_unlock(rwlock_t *lock)
 217 {
 218         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 219         arch_read_unlock(&lock->raw_lock);
 220 }
 221
 222 static inline void debug_write_lock_before(rwlock_t *lock)
 223 {
 224         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 225         RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 226         RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 227                                                         lock, "cpu recursion");
 228 }
 229
 230 static inline void debug_write_lock_after(rwlock_t *lock)
 231 {
 232         lock->owner_cpu = raw_smp_processor_id();
 233         lock->owner = current;
 234 }
 235
 236 static inline void debug_write_unlock(rwlock_t *lock)
 237 {
 238         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 239         RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 240         RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 241                                                         lock, "wrong CPU");
 242         lock->owner = SPINLOCK_OWNER_INIT;
 243         lock->owner_cpu = -1;
 244 }
 245
 246 #if 0           /* This can cause lockups */
 247 static void __write_lock_debug(rwlock_t *lock)
 248 {
 249         u64 i;
 250         u64 loops = loops_per_jiffy * HZ;
 251         int print_once = 1;
 252
 253         for (;;) {
 254                 for (i = 0; i < loops; i++) {
 255                         if (arch_write_trylock(&lock->raw_lock))
 256                                 return;
 257                         __delay(1);
 258                 }
 259                 /* lockup suspected: */
 260                 if (print_once) {
 261                         print_once = 0;
 262                         printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
 263                                         "%s/%d, %p\n",
 264                                 raw_smp_processor_id(), current->comm,
 265                                 current->pid, lock);
 266                         dump_stack();
 267                 }
 268         }
 269 }
 270 #endif
 271
 272 void do_raw_write_lock(rwlock_t *lock)
 273 {
 274         debug_write_lock_before(lock);
 275         arch_write_lock(&lock->raw_lock);
 276         debug_write_lock_after(lock);
 277 }
 278
 279 int do_raw_write_trylock(rwlock_t *lock)
 280 {
 281         int ret = arch_write_trylock(&lock->raw_lock);
 282
 283         if (ret)
 284                 debug_write_lock_after(lock);
 285 #ifndef CONFIG_SMP
 286         /*
 287          * Must not happen on UP:
 288          */
 289         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 290 #endif
 291         return ret;
 292 }
 293
 294 void do_raw_write_unlock(rwlock_t *lock)
 295 {
 296         debug_write_unlock(lock);
 297         arch_write_unlock(&lock->raw_lock);
 298 }