diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-06-06 12:32:43 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-06-07 12:25:50 +0200 |
| commit | f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d (patch) | |
| tree | b461cb0836170eb555b20818802c121c79e76d33 /kernel/lockdep.c | |
| parent | f339b9dc1f03591761d5d930800db24bc0eda1e1 (diff) | |
| download | lwn-f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d.tar.gz lwn-f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d.zip | |
lockdep: Fix lock_is_held() on recursion
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 <lists@die-jansens.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/lockdep.c')
| -rw-r--r-- | kernel/lockdep.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 63437d065ac8..298c9276dfdb 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3426,7 +3426,7 @@ 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() */ raw_local_irq_save(flags); check_flags(flags); |