This is a note to let you know that I've just added the patch titled
lockdep: Fix lock_is_held() on recursion
to the 2.6.33-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.33.git;a=summary
The filename of the patch is:
lockdep-fix-lock_is_held-on-recursion.patch
and it can be found in the queue-2.6.33 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.33 longterm
tree,
please let <[email protected]> know about it.
>From f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <[email protected]>
Date: Mon, 6 Jun 2011 12:32:43 +0200
Subject: lockdep: Fix lock_is_held() on recursion
From: Peter Zijlstra <[email protected]>
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 <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/lockdep.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3252,7 +3252,7 @@ int lock_is_held(struct lockdep_map *loc
int ret = 0;
if (unlikely(current->lockdep_recursion))
- return ret;
+ return 1; /* avoid false negative lockdep_assert_held() */
raw_local_irq_save(flags);
check_flags(flags);
Patches currently in longterm-queue-2.6.33 which might be from
[email protected] are
/home/gregkh/linux/longterm/longterm-queue-2.6.33/queue-2.6.33/rcu-fix-unpaired-rcu_irq_enter-from-locking-selftests.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.33/queue-2.6.33/lockdep-fix-lock_is_held-on-recursion.patch
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