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Message-ID: <20071031154313.15685.72379.stgit@ghaskins-t60p.haskins.net>
Date: Wed, 31 Oct 2007 11:44:05 -0400
From: Gregory Haskins <ghaskins@...ell.com>
To: Greg KH <greg@...ah.com>
Cc: Chuck Ebbert <cebbert@...hat.com>,
Gregory Haskins <ghaskins@...ell.com>,
Peter Zijlstra <peterz@...radead.org>,
stable <stable@...nel.org>, <mingo@...e.hu>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH] lockdep: fix mismatched lockdep_depth/curr_chain_hash
Hi Greg,
Here is the backported version of the patch. I applied it on top of
2.6.22.10. Let me know if you have any issues.
-Greg
------------------------------
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 <ghaskins@...ell.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
kernel/lockdep.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 1a5ff22..072cf25 100644
--- 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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