| From ad62a152f33fdfccf2cb8e0e9dfb4b966d9ead62 Mon Sep 17 00:00:00 2001 |
| From: Peter Zijlstra <a.p.zijlstra@chello.nl> |
| Date: Mon, 6 Jun 2011 12:32:43 +0200 |
| Subject: [PATCH] lockdep: Fix lock_is_held() on recursion |
| |
| 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 <lists@die-jansens.de> |
| Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop |
| Signed-off-by: Ingo Molnar <mingo@elte.hu> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| --- |
| 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() */ |
| |
| raw_local_irq_save(flags); |
| check_flags(flags); |
| -- |
| 1.7.9.3 |
| |
