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: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 734da57..42ae4a5 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1521,7 +1521,7 @@
}
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 @@
* 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 @@
#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 @@
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