linux/kernel/locking/spinlock_debug.c
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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/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
  16void __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
  32EXPORT_SYMBOL(__raw_spin_lock_init);
  33
  34void __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
  50EXPORT_SYMBOL(__rwlock_init);
  51
  52static void spin_dump(raw_spinlock_t *lock, const char *msg)
  53{
  54        struct task_struct *owner = NULL;
  55
  56        if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
  57                owner = lock->owner;
  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, lock->magic,
  64                owner ? owner->comm : "<none>",
  65                owner ? task_pid_nr(owner) : -1,
  66                lock->owner_cpu);
  67        dump_stack();
  68}
  69
  70static 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
  80static inline void
  81debug_spin_lock_before(raw_spinlock_t *lock)
  82{
  83        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  84        SPIN_BUG_ON(lock->owner == current, lock, "recursion");
  85        SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
  86                                                        lock, "cpu recursion");
  87}
  88
  89static inline void debug_spin_lock_after(raw_spinlock_t *lock)
  90{
  91        lock->owner_cpu = raw_smp_processor_id();
  92        lock->owner = current;
  93}
  94
  95static 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        lock->owner = SPINLOCK_OWNER_INIT;
 103        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 */
 110void do_raw_spin_lock(raw_spinlock_t *lock)
 111{
 112        debug_spin_lock_before(lock);
 113        arch_spin_lock(&lock->raw_lock);
 114        debug_spin_lock_after(lock);
 115}
 116
 117int do_raw_spin_trylock(raw_spinlock_t *lock)
 118{
 119        int ret = arch_spin_trylock(&lock->raw_lock);
 120
 121        if (ret)
 122                debug_spin_lock_after(lock);
 123#ifndef CONFIG_SMP
 124        /*
 125         * Must not happen on UP:
 126         */
 127        SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 128#endif
 129        return ret;
 130}
 131
 132void do_raw_spin_unlock(raw_spinlock_t *lock)
 133{
 134        debug_spin_unlock(lock);
 135        arch_spin_unlock(&lock->raw_lock);
 136}
 137
 138static void rwlock_bug(rwlock_t *lock, const char *msg)
 139{
 140        if (!debug_locks_off())
 141                return;
 142
 143        printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 144                msg, raw_smp_processor_id(), current->comm,
 145                task_pid_nr(current), lock);
 146        dump_stack();
 147}
 148
 149#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 150
 151void do_raw_read_lock(rwlock_t *lock)
 152{
 153        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 154        arch_read_lock(&lock->raw_lock);
 155}
 156
 157int do_raw_read_trylock(rwlock_t *lock)
 158{
 159        int ret = arch_read_trylock(&lock->raw_lock);
 160
 161#ifndef CONFIG_SMP
 162        /*
 163         * Must not happen on UP:
 164         */
 165        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 166#endif
 167        return ret;
 168}
 169
 170void do_raw_read_unlock(rwlock_t *lock)
 171{
 172        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 173        arch_read_unlock(&lock->raw_lock);
 174}
 175
 176static inline void debug_write_lock_before(rwlock_t *lock)
 177{
 178        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 179        RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 180        RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 181                                                        lock, "cpu recursion");
 182}
 183
 184static inline void debug_write_lock_after(rwlock_t *lock)
 185{
 186        lock->owner_cpu = raw_smp_processor_id();
 187        lock->owner = current;
 188}
 189
 190static inline void debug_write_unlock(rwlock_t *lock)
 191{
 192        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 193        RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 194        RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 195                                                        lock, "wrong CPU");
 196        lock->owner = SPINLOCK_OWNER_INIT;
 197        lock->owner_cpu = -1;
 198}
 199
 200void do_raw_write_lock(rwlock_t *lock)
 201{
 202        debug_write_lock_before(lock);
 203        arch_write_lock(&lock->raw_lock);
 204        debug_write_lock_after(lock);
 205}
 206
 207int do_raw_write_trylock(rwlock_t *lock)
 208{
 209        int ret = arch_write_trylock(&lock->raw_lock);
 210
 211        if (ret)
 212                debug_write_lock_after(lock);
 213#ifndef CONFIG_SMP
 214        /*
 215         * Must not happen on UP:
 216         */
 217        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 218#endif
 219        return ret;
 220}
 221
 222void do_raw_write_unlock(rwlock_t *lock)
 223{
 224        debug_write_unlock(lock);
 225        arch_write_unlock(&lock->raw_lock);
 226}
 227