mutex-debug.c

  1/*
  2 * Debugging code for mutexes
  3 *
  4 * Started by Ingo Molnar:
  5 *
  6 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  7 *
  8 * lock debugging, locking tree, deadlock detection started by:
  9 *
 10 *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
 11 *  Released under the General Public License (GPL).
 12 */
 13#include <linux/mutex.h>
 14#include <linux/delay.h>
 15#include <linux/device.h>
 16#include <linux/export.h>
 17#include <linux/poison.h>
 18#include <linux/sched.h>
 19#include <linux/spinlock.h>
 20#include <linux/kallsyms.h>
 21#include <linux/interrupt.h>
 22#include <linux/debug_locks.h>
 23
 24#include "mutex.h"
 25
 26/*
 27 * Must be called with lock->wait_lock held.
 28 */
 29void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
 30{
 31	memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
 32	waiter->magic = waiter;
 33	INIT_LIST_HEAD(&waiter->list);
 34	waiter->ww_ctx = MUTEX_POISON_WW_CTX;
 35}
 36
 37void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
 38{
 39	lockdep_assert_held(&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 task_struct *task)
 53{
 54	lockdep_assert_held(&lock->wait_lock);
 55
 56	/* Current thread can't be already blocked (since it's executing!) */
 57	DEBUG_LOCKS_WARN_ON(__get_task_blocked_on(task));
 58}
 59
 60void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
 61			 struct task_struct *task)
 62{
 63	struct mutex *blocked_on = __get_task_blocked_on(task);
 64
 65	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
 66	DEBUG_LOCKS_WARN_ON(waiter->task != task);
 67	DEBUG_LOCKS_WARN_ON(blocked_on && blocked_on != lock);
 68
 69	INIT_LIST_HEAD(&waiter->list);
 70	waiter->task = NULL;
 71}
 72
 73void debug_mutex_unlock(struct mutex *lock)
 74{
 75	if (likely(debug_locks)) {
 76		DEBUG_LOCKS_WARN_ON(lock->magic != lock);
 77		DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
 78	}
 79}
 80
 81void debug_mutex_init(struct mutex *lock)
 82{
 83	lock->magic = lock;
 84}
 85
 86static void devm_mutex_release(void *res)
 87{
 88	mutex_destroy(res);
 89}
 90
 91int __devm_mutex_init(struct device *dev, struct mutex *lock)
 92{
 93	return devm_add_action_or_reset(dev, devm_mutex_release, lock);
 94}
 95EXPORT_SYMBOL_GPL(__devm_mutex_init);
 96
 97/***
 98 * mutex_destroy - mark a mutex unusable
 99 * @lock: the mutex to be destroyed
100 *
101 * This function marks the mutex uninitialized, and any subsequent
102 * use of the mutex is forbidden. The mutex must not be locked when
103 * this function is called.
104 */
105void mutex_destroy(struct mutex *lock)
106{
107	DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
108	lock->magic = NULL;
109}
110
111EXPORT_SYMBOL_GPL(mutex_destroy);