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Date:	Mon, 14 May 2012 22:12:28 -0400
From:	Paul Gortmaker <>
To:	<>, <>
Subject: [34-longterm 052/179] lockdep: Fix lock_is_held() on recursion

From: Peter Zijlstra <>

    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.

commit f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d upstream.

The main lock_is_held() user is lockdep_assert_held(), avoid false
assertions in lockdep_off() sections by unconditionally reporting the
lock is taken.

[ the reason this is important is a lockdep_assert_held() in ttwu()
  which triggers a warning under lockdep_off() as in printk() which
  can trigger another wakeup and lock up due to spinlock
  recursion, as reported and heroically debugged by Arne Jansen ]

Reported-and-tested-by: Arne Jansen <>
Signed-off-by: Peter Zijlstra <>
Cc: Linus Torvalds <>
Signed-off-by: Ingo Molnar <>
Signed-off-by: Paul Gortmaker <>
 kernel/lockdep.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 2594e1c..1571452 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3240,7 +3240,7 @@ int lock_is_held(struct lockdep_map *lock)
 	int ret = 0;
 	if (unlikely(current->lockdep_recursion))
-		return ret;
+		return 1; /* avoid false negative lockdep_assert_held() */

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