Commit-ID: 80e0401e35410a69bfae05b454db8a7187edd6b8 Gitweb: http://git.kernel.org/tip/80e0401e35410a69bfae05b454db8a7187edd6b8 Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> AuthorDate: Fri, 5 Aug 2011 14:26:17 +0200 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Tue, 9 Aug 2011 11:57:35 +0200 lockdep: Fix wrong assumption in match_held_lock match_held_lock() was assuming it was being called on a lock class that had already seen usage. This condition was true for bug-free code using lockdep_assert_held(), since you're in fact holding the lock when calling it. However the assumption fails the moment you assume the assertion can fail, which is the whole point of having the assertion in the first place. Anyway, now that there's more lockdep_is_held() users, notably __rcu_dereference_check(), its much easier to trigger this since we test for a number of locks and we only need to hold any one of them to be good. Reported-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Link: http://lkml.kernel.org/r/1312547787.28695.2.camel@twins Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/lockdep.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 8c24294..91d67ce 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3111,7 +3111,13 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) if (!class) class = look_up_lock_class(lock, 0); - if (DEBUG_LOCKS_WARN_ON(!class)) + /* + * If look_up_lock_class() failed to find a class, we're trying + * to test if we hold a lock that has never yet been acquired. + * Clearly if the lock hasn't been acquired _ever_, we're not + * holding it either, so report failure. + */ + if (!class) return 0; if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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