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493d35863d
Currently, the mutex debug code checks the lock->owner before lock->magic, so a corrupt mutex will most likely result in failing the owner check, rather than the magic check. This change to debug_mutex_unlock does the magic check first, so we have a better idea of what breaks. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
117 lines
3.0 KiB
C
117 lines
3.0 KiB
C
/*
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* kernel/mutex-debug.c
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*
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* Debugging code for mutexes
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*
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* Started by Ingo Molnar:
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*
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* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*
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* lock debugging, locking tree, deadlock detection started by:
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*
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* Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
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* Released under the General Public License (GPL).
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*/
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#include <linux/mutex.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/poison.h>
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#include <linux/spinlock.h>
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#include <linux/kallsyms.h>
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#include <linux/interrupt.h>
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#include <linux/debug_locks.h>
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#include "mutex-debug.h"
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/*
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* Must be called with lock->wait_lock held.
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*/
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void debug_mutex_set_owner(struct mutex *lock, struct thread_info *new_owner)
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{
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lock->owner = new_owner;
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}
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void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
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{
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memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
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waiter->magic = waiter;
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INIT_LIST_HEAD(&waiter->list);
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}
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void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
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{
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SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
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DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
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DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
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DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
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}
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void debug_mutex_free_waiter(struct mutex_waiter *waiter)
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{
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DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
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memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
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}
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void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
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struct thread_info *ti)
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{
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SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
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/* Mark the current thread as blocked on the lock: */
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ti->task->blocked_on = waiter;
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waiter->lock = lock;
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}
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void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
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struct thread_info *ti)
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{
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DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
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DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
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DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
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ti->task->blocked_on = NULL;
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list_del_init(&waiter->list);
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waiter->task = NULL;
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}
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void debug_mutex_unlock(struct mutex *lock)
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{
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if (unlikely(!debug_locks))
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return;
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DEBUG_LOCKS_WARN_ON(lock->magic != lock);
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DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
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DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
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DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
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}
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void debug_mutex_init(struct mutex *lock, const char *name,
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struct lock_class_key *key)
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{
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/*
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* Make sure we are not reinitializing a held lock:
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*/
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debug_check_no_locks_freed((void *)lock, sizeof(*lock));
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lockdep_init_map(&lock->dep_map, name, key, 0);
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#endif
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lock->owner = NULL;
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lock->magic = lock;
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}
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/***
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* mutex_destroy - mark a mutex unusable
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* @lock: the mutex to be destroyed
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*
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* This function marks the mutex uninitialized, and any subsequent
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* use of the mutex is forbidden. The mutex must not be locked when
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* this function is called.
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*/
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void mutex_destroy(struct mutex *lock)
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{
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DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
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lock->magic = NULL;
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}
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EXPORT_SYMBOL_GPL(mutex_destroy);
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