[one more patch added to the 2.6.22-stable queue]
From: Gregory Haskins <[email protected]>
patch 3aa416b07f0adf01c090baab26fb70c35ec17623 in mainline.
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.
[ peterz: this might explain some of the lockdep is so _slow_ complaints. ]
[ mingo: this does not impact the correctness of validation, but may slow
down future operations significantly, if the chain gets very long. ]
Signed-off-by: Gregory Haskins <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2166,7 +2166,6 @@ out_calc_hash:
}
#endif
chain_key = iterate_chain_key(chain_key, id);
- curr->curr_chain_key = chain_key;
/*
* Trylock needs to maintain the stack of held locks, but it
@@ -2215,6 +2214,7 @@ out_calc_hash:
if (unlikely(!debug_locks))
return 0;
+ curr->curr_chain_key = chain_key;
curr->lockdep_depth++;
check_chain_key(curr);
#ifdef CONFIG_DEBUG_LOCKDEP
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