On Mon, Aug 10, 2015 at 05:52:47PM +0800, Boqun Feng wrote: > Hi Peter and Ingo, > > I'm now learning the code of lockdep and find that nested lock may not > be handled correctly because we fail to take held_lock merging into > consideration. I come up with an example and hope that could explain my > concern. > > Please consider this lock/unlock sequence, I also put a patch ading this > sequence as a test into locking-selftest: > > (lock_X1 and lock_X2 belong to the same lock class X, lock_Y1 belongs to > another lock class Y) > > spin_lock(&lock_X1); > spin_lock(&lock_Y1); > spin_lock_nested_lock(&lock_X2, &lock_X1); > spin_unlock(&lock_Y1); > spin_unlock(&lock_X2); > spin_unlock(&lock_X1); > > > This is totally legal in current lockdep rules, right?
Yuck, I'd say no. That's quite horrible. Why would you ever want to do that? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
