/*
   * kernel/mutex-debug.c
   *
   * Debugging code for mutexes
   *
   * Started by Ingo Molnar:
   *
   *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   *
   * lock debugging, locking tree, deadlock detection started by:
   *
   *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
   *  Released under the General Public License (GPL).
   */
  #include <linux/mutex.h>

  #include <linux/delay.h>

  #include <linux/export.h>

  #include <linux/poison.h>

  #include <linux/sched.h>

  #include <linux/spinlock.h>
  #include <linux/kallsyms.h>
  #include <linux/interrupt.h>

  #include <linux/debug_locks.h>

  #include "mutex-debug.h"
  
  /*

   * Must be called with lock->wait_lock held.
   */

  void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)

  {

  	memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));

  	waiter->magic = waiter;
  	INIT_LIST_HEAD(&waiter->list);
  }
  
  void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  {

  	SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  	DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  	DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));

  }
  
  void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  {

  	DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));

  	memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));

  }
  
  void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,

  			    struct thread_info *ti)

  {

  	SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));

  	/* Mark the current thread as blocked on the lock: */
  	ti->task->blocked_on = waiter;

  }
  
  void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  			 struct thread_info *ti)
  {

  	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  	DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
  	DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);

  	ti->task->blocked_on = NULL;
  
  	list_del_init(&waiter->list);
  	waiter->task = NULL;
  }
  
  void debug_mutex_unlock(struct mutex *lock)
  {

  	if (likely(debug_locks)) {
  		DEBUG_LOCKS_WARN_ON(lock->magic != lock);

  		if (!lock->owner)
  			DEBUG_LOCKS_WARN_ON(!lock->owner);
  		else
  			DEBUG_LOCKS_WARN_ON(lock->owner != current);

  		DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);

  	}

  
  	/*
  	 * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug
  	 * mutexes so that we can do it here after we've verified state.
  	 */

  	mutex_clear_owner(lock);

  	atomic_set(&lock->count, 1);

  }

  void debug_mutex_init(struct mutex *lock, const char *name,
  		      struct lock_class_key *key)

  {

  #ifdef CONFIG_DEBUG_LOCK_ALLOC

  	/*
  	 * Make sure we are not reinitializing a held lock:
  	 */

  	debug_check_no_locks_freed((void *)lock, sizeof(*lock));

  	lockdep_init_map(&lock->dep_map, name, key, 0);

  #endif

  	lock->magic = lock;
  }
  
  /***
   * mutex_destroy - mark a mutex unusable
   * @lock: the mutex to be destroyed
   *
   * This function marks the mutex uninitialized, and any subsequent
   * use of the mutex is forbidden. The mutex must not be locked when
   * this function is called.
   */

  void mutex_destroy(struct mutex *lock)

  {

  	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));

  	lock->magic = NULL;
  }
  
  EXPORT_SYMBOL_GPL(mutex_destroy);