From f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 6 Jun 2011 12:32:43 +0200 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop Signed-off-by: Ingo Molnar --- kernel/lockdep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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);