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 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 = READ_ONCE(lock->owner);
  55
  56         if (owner == SPINLOCK_OWNER_INIT)
  57                 owner = NULL;
  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, READ_ONCE(lock->magic),
  64                 owner ? owner->comm : "<none>",
  65                 owner ? task_pid_nr(owner) : -1,
  66                 READ_ONCE(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(READ_ONCE(lock->magic) != SPINLOCK_MAGIC, lock, "bad magic");
  84         SPIN_BUG_ON(READ_ONCE(lock->owner) == current, lock, "recursion");
  85         SPIN_BUG_ON(READ_ONCE(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         WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
  92         WRITE_ONCE(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         WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
 103         WRITE_ONCE(lock->owner_cpu, -1);
 104 }
 105
 106 /*
 107  * We are now relying on the NMI watchdog to detect lockup instead of doing
 108  * the detection here with an unfair lock which can cause problem of its own.
 109  */
 110 void do_raw_spin_lock(raw_spinlock_t *lock)
 111 {
 112         debug_spin_lock_before(lock);
 113         arch_spin_lock(&lock->raw_lock);
 114         mmiowb_spin_lock();
 115         debug_spin_lock_after(lock);
 116 }
 117
 118 int do_raw_spin_trylock(raw_spinlock_t *lock)
 119 {
 120         int ret = arch_spin_trylock(&lock->raw_lock);
 121
 122         if (ret) {
 123                 mmiowb_spin_lock();
 124                 debug_spin_lock_after(lock);
 125         }
 126 #ifndef CONFIG_SMP
 127         /*
 128          * Must not happen on UP:
 129          */
 130         SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 131 #endif
 132         return ret;
 133 }
 134
 135 void do_raw_spin_unlock(raw_spinlock_t *lock)
 136 {
 137         mmiowb_spin_unlock();
 138         debug_spin_unlock(lock);
 139         arch_spin_unlock(&lock->raw_lock);
 140 }
 141
 142 static void rwlock_bug(rwlock_t *lock, const char *msg)
 143 {
 144         if (!debug_locks_off())
 145                 return;
 146
 147         printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 148                 msg, raw_smp_processor_id(), current->comm,
 149                 task_pid_nr(current), lock);
 150         dump_stack();
 151 }
 152
 153 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 154
 155 void do_raw_read_lock(rwlock_t *lock)
 156 {
 157         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 158         arch_read_lock(&lock->raw_lock);
 159 }
 160
 161 int do_raw_read_trylock(rwlock_t *lock)
 162 {
 163         int ret = arch_read_trylock(&lock->raw_lock);
 164
 165 #ifndef CONFIG_SMP
 166         /*
 167          * Must not happen on UP:
 168          */
 169         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 170 #endif
 171         return ret;
 172 }
 173
 174 void do_raw_read_unlock(rwlock_t *lock)
 175 {
 176         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 177         arch_read_unlock(&lock->raw_lock);
 178 }
 179
 180 static inline void debug_write_lock_before(rwlock_t *lock)
 181 {
 182         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 183         RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 184         RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 185                                                         lock, "cpu recursion");
 186 }
 187
 188 static inline void debug_write_lock_after(rwlock_t *lock)
 189 {
 190         WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
 191         WRITE_ONCE(lock->owner, current);
 192 }
 193
 194 static inline void debug_write_unlock(rwlock_t *lock)
 195 {
 196         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 197         RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 198         RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 199                                                         lock, "wrong CPU");
 200         WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
 201         WRITE_ONCE(lock->owner_cpu, -1);
 202 }
 203
 204 void do_raw_write_lock(rwlock_t *lock)
 205 {
 206         debug_write_lock_before(lock);
 207         arch_write_lock(&lock->raw_lock);
 208         debug_write_lock_after(lock);
 209 }
 210
 211 int do_raw_write_trylock(rwlock_t *lock)
 212 {
 213         int ret = arch_write_trylock(&lock->raw_lock);
 214
 215         if (ret)
 216                 debug_write_lock_after(lock);
 217 #ifndef CONFIG_SMP
 218         /*
 219          * Must not happen on UP:
 220          */
 221         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 222 #endif
 223         return ret;
 224 }
 225
 226 void do_raw_write_unlock(rwlock_t *lock)
 227 {
 228         debug_write_unlock(lock);
 229         arch_write_unlock(&lock->raw_lock);
 230 }