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