[patch 01/13] lockdep: fix mismatched lockdep_depth/curr_chain_hash

[Greg KH]

-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Gregory Haskins <ghaskins@xxxxxxxxxx>

patch 3aa416b07f0adf01c090baab26fb70c35ec17623 in mainline.

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: Gregory Haskins <ghaskins@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Cc: Chuck Ebbert <cebbert@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 kernel/lockdep.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1521,7 +1521,7 @@ cache_hit:
 }
 
 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_st
 	 * 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_st
 #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
 		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

-- 
-
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