Messages in this thread Patch in this message | | | Date | Tue, 7 Jun 2011 12:02:29 GMT | From | tip-bot for Peter Zijlstra <> | Subject | [tip:sched/urgent] lockdep: Fix lock_is_held() on recursion |
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Commit-ID: f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d Gitweb: http://git.kernel.org/tip/f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d Author: Peter Zijlstra <a.p.zijlstra@chello.nl> AuthorDate: Mon, 6 Jun 2011 12:32:43 +0200 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Tue, 7 Jun 2011 12:25:50 +0200
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> --- kernel/lockdep.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 63437d0..298c927 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);
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