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Commit 3aa416b0 authored by Gregory Haskins's avatar Gregory Haskins Committed by Peter Zijlstra
Browse files

lockdep: fix mismatched lockdep_depth/curr_chain_hash 


It is possible for the current->curr_chain_key to become inconsistent with the
current index if the chain fails to validate.  The end result is that future
lock_acquire() operations may inadvertently fail to find a hit in the cache
resulting in a new node being added to the graph for every acquire.

Signed-off-by: default avatarGregory Haskins <ghaskins@novell.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 94c61c0a

kernel/lockdep.c

+5 −5
Original line number Diff line number Diff line
@@ -1521,7 +1521,7 @@ static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class) 
}



static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,

	       	struct held_lock *hlock, int chain_head)

	       	struct held_lock *hlock, int chain_head, u64 chain_key)

{

	/*

	 * Trylock needs to maintain the stack of held locks, but it
@@ -1534,7 +1534,7 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, 
	 * graph_lock for us)

	 */

	if (!hlock->trylock && (hlock->check == 2) &&

			lookup_chain_cache(curr->curr_chain_key, hlock->class)) {

			lookup_chain_cache(chain_key, hlock->class)) {

		/*

		 * Check whether last held lock:

		 *
@@ -1576,7 +1576,7 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, 
#else

static inline int validate_chain(struct task_struct *curr,

	       	struct lockdep_map *lock, struct held_lock *hlock,

		int chain_head)

		int chain_head, u64 chain_key)

{

	return 1;

}
@@ -2450,11 +2450,11 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, 
		chain_head = 1;

	}

	chain_key = iterate_chain_key(chain_key, id);

	curr->curr_chain_key = chain_key;



	if (!validate_chain(curr, lock, hlock, chain_head))

	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))

		return 0;



	curr->curr_chain_key = chain_key;

	curr->lockdep_depth++;

	check_chain_key(curr);

#ifdef CONFIG_DEBUG_LOCKDEP