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 #include <linux/pid.h>
  16
  17 void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
  18                           struct lock_class_key *key, short inner)
  19 {
  20 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  21         /*
  22          * Make sure we are not reinitializing a held lock:
  23          */
  24         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  25         lockdep_init_map_wait(&lock->dep_map, name, key, 0, inner);
  26 #endif
  27         lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  28         lock->magic = SPINLOCK_MAGIC;
  29         lock->owner = SPINLOCK_OWNER_INIT;
  30         lock->owner_cpu = -1;
  31 }
  32
  33 EXPORT_SYMBOL(__raw_spin_lock_init);
  34
  35 #ifndef CONFIG_PREEMPT_RT
  36 void __rwlock_init(rwlock_t *lock, const char *name,
  37                    struct lock_class_key *key)
  38 {
  39 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  40         /*
  41          * Make sure we are not reinitializing a held lock:
  42          */
  43         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  44         lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_CONFIG);
  45 #endif
  46         lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
  47         lock->magic = RWLOCK_MAGIC;
  48         lock->owner = SPINLOCK_OWNER_INIT;
  49         lock->owner_cpu = -1;
  50 }
  51
  52 EXPORT_SYMBOL(__rwlock_init);
  53 #endif
  54
  55 static void spin_dump(raw_spinlock_t *lock, const char *msg)
  56 {
  57         struct task_struct *owner = READ_ONCE(lock->owner);
  58
  59         if (owner == SPINLOCK_OWNER_INIT)
  60                 owner = NULL;
  61         printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
  62                 msg, raw_smp_processor_id(),
  63                 current->comm, task_pid_nr(current));
  64         printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
  65                         ".owner_cpu: %d\n",
  66                 lock, READ_ONCE(lock->magic),
  67                 owner ? owner->comm : "<none>",
  68                 owner ? task_pid_nr(owner) : -1,
  69                 READ_ONCE(lock->owner_cpu));
  70         dump_stack();
  71 }
  72
  73 static void spin_bug(raw_spinlock_t *lock, const char *msg)
  74 {
  75         if (!debug_locks_off())
  76                 return;
  77
  78         spin_dump(lock, msg);
  79 }
  80
  81 #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
  82
  83 static inline void
  84 debug_spin_lock_before(raw_spinlock_t *lock)
  85 {
  86         SPIN_BUG_ON(READ_ONCE(lock->magic) != SPINLOCK_MAGIC, lock, "bad magic");
  87         SPIN_BUG_ON(READ_ONCE(lock->owner) == current, lock, "recursion");
  88         SPIN_BUG_ON(READ_ONCE(lock->owner_cpu) == raw_smp_processor_id(),
  89                                                         lock, "cpu recursion");
  90 }
  91
  92 static inline void debug_spin_lock_after(raw_spinlock_t *lock)
  93 {
  94         WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
  95         WRITE_ONCE(lock->owner, current);
  96 }
  97
  98 static inline void debug_spin_unlock(raw_spinlock_t *lock)
  99 {
 100         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
 101         SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
 102         SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
 103         SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 104                                                         lock, "wrong CPU");
 105         WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
 106         WRITE_ONCE(lock->owner_cpu, -1);
 107 }
 108
 109 /*
 110  * We are now relying on the NMI watchdog to detect lockup instead of doing
 111  * the detection here with an unfair lock which can cause problem of its own.
 112  */
 113 void do_raw_spin_lock(raw_spinlock_t *lock)
 114 {
 115         debug_spin_lock_before(lock);
 116         arch_spin_lock(&lock->raw_lock);
 117         mmiowb_spin_lock();
 118         debug_spin_lock_after(lock);
 119 }
 120
 121 int do_raw_spin_trylock(raw_spinlock_t *lock)
 122 {
 123         int ret = arch_spin_trylock(&lock->raw_lock);
 124
 125         if (ret) {
 126                 mmiowb_spin_lock();
 127                 debug_spin_lock_after(lock);
 128         }
 129 #ifndef CONFIG_SMP
 130         /*
 131          * Must not happen on UP:
 132          */
 133         SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 134 #endif
 135         return ret;
 136 }
 137
 138 void do_raw_spin_unlock(raw_spinlock_t *lock)
 139 {
 140         mmiowb_spin_unlock();
 141         debug_spin_unlock(lock);
 142         arch_spin_unlock(&lock->raw_lock);
 143 }
 144
 145 #ifndef CONFIG_PREEMPT_RT
 146 static void rwlock_bug(rwlock_t *lock, const char *msg)
 147 {
 148         if (!debug_locks_off())
 149                 return;
 150
 151         printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 152                 msg, raw_smp_processor_id(), current->comm,
 153                 task_pid_nr(current), lock);
 154         dump_stack();
 155 }
 156
 157 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 158
 159 void do_raw_read_lock(rwlock_t *lock)
 160 {
 161         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 162         arch_read_lock(&lock->raw_lock);
 163 }
 164
 165 int do_raw_read_trylock(rwlock_t *lock)
 166 {
 167         int ret = arch_read_trylock(&lock->raw_lock);
 168
 169 #ifndef CONFIG_SMP
 170         /*
 171          * Must not happen on UP:
 172          */
 173         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 174 #endif
 175         return ret;
 176 }
 177
 178 void do_raw_read_unlock(rwlock_t *lock)
 179 {
 180         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 181         arch_read_unlock(&lock->raw_lock);
 182 }
 183
 184 static inline void debug_write_lock_before(rwlock_t *lock)
 185 {
 186         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 187         RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 188         RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 189                                                         lock, "cpu recursion");
 190 }
 191
 192 static inline void debug_write_lock_after(rwlock_t *lock)
 193 {
 194         WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
 195         WRITE_ONCE(lock->owner, current);
 196 }
 197
 198 static inline void debug_write_unlock(rwlock_t *lock)
 199 {
 200         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 201         RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 202         RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 203                                                         lock, "wrong CPU");
 204         WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
 205         WRITE_ONCE(lock->owner_cpu, -1);
 206 }
 207
 208 void do_raw_write_lock(rwlock_t *lock)
 209 {
 210         debug_write_lock_before(lock);
 211         arch_write_lock(&lock->raw_lock);
 212         debug_write_lock_after(lock);
 213 }
 214
 215 int do_raw_write_trylock(rwlock_t *lock)
 216 {
 217         int ret = arch_write_trylock(&lock->raw_lock);
 218
 219         if (ret)
 220                 debug_write_lock_after(lock);
 221 #ifndef CONFIG_SMP
 222         /*
 223          * Must not happen on UP:
 224          */
 225         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 226 #endif
 227         return ret;
 228 }
 229
 230 void do_raw_write_unlock(rwlock_t *lock)
 231 {
 232         debug_write_unlock(lock);
 233         arch_write_unlock(&lock->raw_lock);
 234 }
 235
 236 #endif /* !CONFIG_PREEMPT_RT */