1/*
  2 * kernel/mutex-debug.c
  3 *
  4 * Debugging code for mutexes
  5 *
  6 * Started by Ingo Molnar:
  7 *
  8 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  9 *
 10 * lock debugging, locking tree, deadlock detection started by:
 11 *
 12 *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
 13 *  Released under the General Public License (GPL).
 14 */
 15#include <linux/mutex.h>
 16#include <linux/delay.h>
 17#include <linux/module.h>
 18#include <linux/poison.h>
 19#include <linux/sched.h>
 20#include <linux/spinlock.h>
 21#include <linux/kallsyms.h>
 22#include <linux/interrupt.h>
 23#include <linux/debug_locks.h>
 24
 25#include "mutex-debug.h"
 26
 27/*
 28 * Must be called with lock->wait_lock held.
 29 */
 30void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
 31{
 32	memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
 33	waiter->magic = waiter;
 34	INIT_LIST_HEAD(&waiter->list);
 35}
 36
 37void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
 38{
 39	SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
 40	DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
 41	DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
 42	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
 43}
 44
 45void debug_mutex_free_waiter(struct mutex_waiter *waiter)
 46{
 47	DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
 48	memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
 49}
 50
 51void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
 52			    struct thread_info *ti)
 53{
 54	SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
 55
 56	/* Mark the current thread as blocked on the lock: */
 57	ti->task->blocked_on = waiter;
 58}
 59
 60void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
 61			 struct thread_info *ti)
 62{
 63	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
 64	DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
 65	DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
 66	ti->task->blocked_on = NULL;
 67
 68	list_del_init(&waiter->list);
 69	waiter->task = NULL;
 70}
 71
 72void debug_mutex_unlock(struct mutex *lock)
 73{
 74	if (unlikely(!debug_locks))
 75		return;
 76
 77	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
 78	DEBUG_LOCKS_WARN_ON(lock->owner != current);
 79	DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
 80	mutex_clear_owner(lock);
 81}
 82
 83void debug_mutex_init(struct mutex *lock, const char *name,
 84		      struct lock_class_key *key)
 85{
 86#ifdef CONFIG_DEBUG_LOCK_ALLOC
 87	/*
 88	 * Make sure we are not reinitializing a held lock:
 89	 */
 90	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 91	lockdep_init_map(&lock->dep_map, name, key, 0);
 92#endif
 93	lock->magic = lock;
 94}
 95
 96/***
 97 * mutex_destroy - mark a mutex unusable
 98 * @lock: the mutex to be destroyed
 99 *
100 * This function marks the mutex uninitialized, and any subsequent
101 * use of the mutex is forbidden. The mutex must not be locked when
102 * this function is called.
103 */
104void mutex_destroy(struct mutex *lock)
105{
106	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
107	lock->magic = NULL;
108}
109
110EXPORT_SYMBOL_GPL(mutex_destroy);