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