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, 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
  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_wait(&lock->dep_map, name, key, 0, LD_WAIT_CONFIG);
  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 = 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
  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(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
  89static 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
  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        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 */
 110void 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
 118int 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
 135void 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
 142static 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
 155void 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
 161int 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
 174void 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
 180static 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
 188static 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
 194static 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
 204void 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
 211int 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
 226void do_raw_write_unlock(rwlock_t *lock)
 227{
 228        debug_write_unlock(lock);
 229        arch_write_unlock(&lock->raw_lock);
 230}
 231