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, short inner)
  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_wait(&lock->dep_map, name, key, 0, inner);
  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
  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_wait(&lock->dep_map, name, key, 0, LD_WAIT_CONFIG);
  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 = READ_ONCE(lock->owner);
  57
  58         if (owner == SPINLOCK_OWNER_INIT)
  59                 owner = NULL;
  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, READ_ONCE(lock->magic),
  66                 owner ? owner->comm : "<none>",
  67                 owner ? task_pid_nr(owner) : -1,
  68                 READ_ONCE(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(READ_ONCE(lock->magic) != SPINLOCK_MAGIC, lock, "bad magic");
  86         SPIN_BUG_ON(READ_ONCE(lock->owner) == current, lock, "recursion");
  87         SPIN_BUG_ON(READ_ONCE(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         WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
  94         WRITE_ONCE(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         WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
 105         WRITE_ONCE(lock->owner_cpu, -1);
 106 }
 107
 108 /*
 109  * We are now relying on the NMI watchdog to detect lockup instead of doing
 110  * the detection here with an unfair lock which can cause problem of its own.
 111  */
 112 void do_raw_spin_lock(raw_spinlock_t *lock)
 113 {
 114         debug_spin_lock_before(lock);
 115         arch_spin_lock(&lock->raw_lock);
 116         mmiowb_spin_lock();
 117         debug_spin_lock_after(lock);
 118 }
 119
 120 int do_raw_spin_trylock(raw_spinlock_t *lock)
 121 {
 122         int ret = arch_spin_trylock(&lock->raw_lock);
 123
 124         if (ret) {
 125                 mmiowb_spin_lock();
 126                 debug_spin_lock_after(lock);
 127         }
 128 #ifndef CONFIG_SMP
 129         /*
 130          * Must not happen on UP:
 131          */
 132         SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 133 #endif
 134         return ret;
 135 }
 136
 137 void do_raw_spin_unlock(raw_spinlock_t *lock)
 138 {
 139         mmiowb_spin_unlock();
 140         debug_spin_unlock(lock);
 141         arch_spin_unlock(&lock->raw_lock);
 142 }
 143
 144 #ifndef CONFIG_PREEMPT_RT
 145 static void rwlock_bug(rwlock_t *lock, const char *msg)
 146 {
 147         if (!debug_locks_off())
 148                 return;
 149
 150         printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 151                 msg, raw_smp_processor_id(), current->comm,
 152                 task_pid_nr(current), lock);
 153         dump_stack();
 154 }
 155
 156 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 157
 158 void do_raw_read_lock(rwlock_t *lock)
 159 {
 160         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 161         arch_read_lock(&lock->raw_lock);
 162 }
 163
 164 int do_raw_read_trylock(rwlock_t *lock)
 165 {
 166         int ret = arch_read_trylock(&lock->raw_lock);
 167
 168 #ifndef CONFIG_SMP
 169         /*
 170          * Must not happen on UP:
 171          */
 172         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 173 #endif
 174         return ret;
 175 }
 176
 177 void do_raw_read_unlock(rwlock_t *lock)
 178 {
 179         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 180         arch_read_unlock(&lock->raw_lock);
 181 }
 182
 183 static inline void debug_write_lock_before(rwlock_t *lock)
 184 {
 185         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 186         RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 187         RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 188                                                         lock, "cpu recursion");
 189 }
 190
 191 static inline void debug_write_lock_after(rwlock_t *lock)
 192 {
 193         WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
 194         WRITE_ONCE(lock->owner, current);
 195 }
 196
 197 static inline void debug_write_unlock(rwlock_t *lock)
 198 {
 199         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 200         RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 201         RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 202                                                         lock, "wrong CPU");
 203         WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
 204         WRITE_ONCE(lock->owner_cpu, -1);
 205 }
 206
 207 void do_raw_write_lock(rwlock_t *lock)
 208 {
 209         debug_write_lock_before(lock);
 210         arch_write_lock(&lock->raw_lock);
 211         debug_write_lock_after(lock);
 212 }
 213
 214 int do_raw_write_trylock(rwlock_t *lock)
 215 {
 216         int ret = arch_write_trylock(&lock->raw_lock);
 217
 218         if (ret)
 219                 debug_write_lock_after(lock);
 220 #ifndef CONFIG_SMP
 221         /*
 222          * Must not happen on UP:
 223          */
 224         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 225 #endif
 226         return ret;
 227 }
 228
 229 void do_raw_write_unlock(rwlock_t *lock)
 230 {
 231         debug_write_unlock(lock);
 232         arch_write_unlock(&lock->raw_lock);
 233 }
 234
 235 #endif /* !CONFIG_PREEMPT_RT */