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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-06-06 12:32:43 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-06-23 15:28:40 -0700 |
| commit | 904b61178e165b531ea656c200719d2e585d313d (patch) | |
| tree | cbdb67dccdcbd3122a5c7c7e404948293ef2dc06 | |
| parent | 45c40b629e8bef5127c8d4e4575a9bcabcbf2125 (diff) | |
| download | kernel-common-904b61178e165b531ea656c200719d2e585d313d.tar.gz kernel-common-904b61178e165b531ea656c200719d2e585d313d.tar.bz2 kernel-common-904b61178e165b531ea656c200719d2e585d313d.zip | |
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: Greg Kroah-Hartman <gregkh@suse.de>
| -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 493a0efbb869..b029c95791d6 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3252,7 +3252,7 @@ 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); |