/* * 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);