kernel/kernel/locking/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 #ifndef CONFIG_PREEMPT_RT_FULL
  35 void __rwlock_init(rwlock_t *lock, const char *name,
  36                    struct lock_class_key *key)
  37 {
  38 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  39         /*
  40          * Make sure we are not reinitializing a held lock:
  41          */
  42         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  43         lockdep_init_map(&lock->dep_map, name, key, 0);
  44 #endif
  45         lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
  46         lock->magic = RWLOCK_MAGIC;
  47         lock->owner = SPINLOCK_OWNER_INIT;
  48         lock->owner_cpu = -1;
  49 }
  50
  51 EXPORT_SYMBOL(__rwlock_init);
  52 #endif
  53
  54 static void spin_dump(raw_spinlock_t *lock, const char *msg)
  55 {
  56         struct task_struct *owner = NULL;
  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, task_pid_nr(current));
  63         printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
  64                         ".owner_cpu: %d\n",
  65                 lock, lock->magic,
  66                 owner ? owner->comm : "<none>",
  67                 owner ? task_pid_nr(owner) : -1,
  68                 lock->owner_cpu);
  69         dump_stack();
  70 }
  71
  72 static void spin_bug(raw_spinlock_t *lock, const char *msg)
  73 {
  74         if (!debug_locks_off())
  75                 return;
  76
  77         spin_dump(lock, msg);
  78 }
  79
  80 #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
  81
  82 static inline void
  83 debug_spin_lock_before(raw_spinlock_t *lock)
  84 {
  85         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  86         SPIN_BUG_ON(lock->owner == current, lock, "recursion");
  87         SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
  88                                                         lock, "cpu recursion");
  89 }
  90
  91 static inline void debug_spin_lock_after(raw_spinlock_t *lock)
  92 {
  93         lock->owner_cpu = raw_smp_processor_id();
  94         lock->owner = current;
  95 }
  96
  97 static inline void debug_spin_unlock(raw_spinlock_t *lock)
  98 {
  99         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
 100         SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
 101         SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
 102         SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 103                                                         lock, "wrong CPU");
 104         lock->owner = SPINLOCK_OWNER_INIT;
 105         lock->owner_cpu = -1;
 106 }
 107
 108 static void __spin_lock_debug(raw_spinlock_t *lock)
 109 {
 110         u64 i;
 111         u64 loops = loops_per_jiffy * HZ;
 112
 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         spin_dump(lock, "lockup suspected");
 120 #ifdef CONFIG_SMP
 121         trigger_all_cpu_backtrace();
 122 #endif
 123
 124         /*
 125          * The trylock above was causing a livelock.  Give the lower level arch
 126          * specific lock code a chance to acquire the lock. We have already
 127          * printed a warning/backtrace at this point. The non-debug arch
 128          * specific code might actually succeed in acquiring the lock.  If it is
 129          * not successful, the end-result is the same - there is no forward
 130          * progress.
 131          */
 132         arch_spin_lock(&lock->raw_lock);
 133 }
 134
 135 void do_raw_spin_lock(raw_spinlock_t *lock)
 136 {
 137         debug_spin_lock_before(lock);
 138         if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
 139                 __spin_lock_debug(lock);
 140         debug_spin_lock_after(lock);
 141 }
 142
 143 int do_raw_spin_trylock(raw_spinlock_t *lock)
 144 {
 145         int ret = arch_spin_trylock(&lock->raw_lock);
 146
 147         if (ret)
 148                 debug_spin_lock_after(lock);
 149 #ifndef CONFIG_SMP
 150         /*
 151          * Must not happen on UP:
 152          */
 153         SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 154 #endif
 155         return ret;
 156 }
 157
 158 void do_raw_spin_unlock(raw_spinlock_t *lock)
 159 {
 160         debug_spin_unlock(lock);
 161         arch_spin_unlock(&lock->raw_lock);
 162 }
 163
 164 #ifndef CONFIG_PREEMPT_RT_FULL
 165 static void rwlock_bug(rwlock_t *lock, const char *msg)
 166 {
 167         if (!debug_locks_off())
 168                 return;
 169
 170         printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 171                 msg, raw_smp_processor_id(), current->comm,
 172                 task_pid_nr(current), lock);
 173         dump_stack();
 174 }
 175
 176 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 177
 178 #if 0           /* __write_lock_debug() can lock up - maybe this can too? */
 179 static void __read_lock_debug(rwlock_t *lock)
 180 {
 181         u64 i;
 182         u64 loops = loops_per_jiffy * HZ;
 183         int print_once = 1;
 184
 185         for (;;) {
 186                 for (i = 0; i < loops; i++) {
 187                         if (arch_read_trylock(&lock->raw_lock))
 188                                 return;
 189                         __delay(1);
 190                 }
 191                 /* lockup suspected: */
 192                 if (print_once) {
 193                         print_once = 0;
 194                         printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
 195                                         "%s/%d, %p\n",
 196                                 raw_smp_processor_id(), current->comm,
 197                                 current->pid, lock);
 198                         dump_stack();
 199                 }
 200         }
 201 }
 202 #endif
 203
 204 void do_raw_read_lock(rwlock_t *lock)
 205 {
 206         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 207         arch_read_lock(&lock->raw_lock);
 208 }
 209
 210 int do_raw_read_trylock(rwlock_t *lock)
 211 {
 212         int ret = arch_read_trylock(&lock->raw_lock);
 213
 214 #ifndef CONFIG_SMP
 215         /*
 216          * Must not happen on UP:
 217          */
 218         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 219 #endif
 220         return ret;
 221 }
 222
 223 void do_raw_read_unlock(rwlock_t *lock)
 224 {
 225         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 226         arch_read_unlock(&lock->raw_lock);
 227 }
 228
 229 static inline void debug_write_lock_before(rwlock_t *lock)
 230 {
 231         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 232         RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 233         RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 234                                                         lock, "cpu recursion");
 235 }
 236
 237 static inline void debug_write_lock_after(rwlock_t *lock)
 238 {
 239         lock->owner_cpu = raw_smp_processor_id();
 240         lock->owner = current;
 241 }
 242
 243 static inline void debug_write_unlock(rwlock_t *lock)
 244 {
 245         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 246         RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 247         RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 248                                                         lock, "wrong CPU");
 249         lock->owner = SPINLOCK_OWNER_INIT;
 250         lock->owner_cpu = -1;
 251 }
 252
 253 #if 0           /* This can cause lockups */
 254 static void __write_lock_debug(rwlock_t *lock)
 255 {
 256         u64 i;
 257         u64 loops = loops_per_jiffy * HZ;
 258         int print_once = 1;
 259
 260         for (;;) {
 261                 for (i = 0; i < loops; i++) {
 262                         if (arch_write_trylock(&lock->raw_lock))
 263                                 return;
 264                         __delay(1);
 265                 }
 266                 /* lockup suspected: */
 267                 if (print_once) {
 268                         print_once = 0;
 269                         printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
 270                                         "%s/%d, %p\n",
 271                                 raw_smp_processor_id(), current->comm,
 272                                 current->pid, lock);
 273                         dump_stack();
 274                 }
 275         }
 276 }
 277 #endif
 278
 279 void do_raw_write_lock(rwlock_t *lock)
 280 {
 281         debug_write_lock_before(lock);
 282         arch_write_lock(&lock->raw_lock);
 283         debug_write_lock_after(lock);
 284 }
 285
 286 int do_raw_write_trylock(rwlock_t *lock)
 287 {
 288         int ret = arch_write_trylock(&lock->raw_lock);
 289
 290         if (ret)
 291                 debug_write_lock_after(lock);
 292 #ifndef CONFIG_SMP
 293         /*
 294          * Must not happen on UP:
 295          */
 296         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 297 #endif
 298         return ret;
 299 }
 300
 301 void do_raw_write_unlock(rwlock_t *lock)
 302 {
 303         debug_write_unlock(lock);
 304         arch_write_unlock(&lock->raw_lock);
 305 }
 306
 307 #endif