On Thu, 2017-10-19 at 17:34 +0200, Thomas Gleixner wrote: > I really disagree with your reasoning completely > > 1) When lockdep was introduced more than ten years ago it was far from > perfect and we spent a reasonable amount of time to improve it, analyze > false positives and add the missing annotations all over the tree. That > was a process which took years. > > 2) Surely nobody is interested in wasting time on analyzing false > positives, but your (and other peoples) attidute of 'none of my > business' is what makes kernel development extremly frustrating. > > It should be in the interest of everybody involved in kernel development > to help with improving such features and not to lean back and wait for > others to bring it into a shape which allows you to use it as you see > fit. > > That's not how community works and lockdep would not be in the shape it is > today, if only a handful of people would have used and improved it. Such > things only work when used widely and when we get enough information so we > can address the weak spots. Hello Thomas, It seems like you are missing my point. Cross-release checking is really *broken* as a concept. It is impossible to improve it to the same reliability level as the kernel v4.13 lockdep code. Hence my request to make it possible to disable cross-release checking if PROVE_LOCKING is enabled. Consider the following example from the cross-release documentation: TASK X TASK Y ------ ------ acquire AX acquire B /* A dependency 'AX -> B' exists */ release B release AX held by Y My understanding is that the cross-release code will add (AX, B) to the lock order graph after having encountered the above code. I think that's wrong because if the following sequence (Y: acquire AX, X: acquire B, X: release B) is encountered again that there is no guarantee that AX can only be released by X. Any task other than X could release that synchronization object too. Bart.��.n������g��� �a��� �&ޖ)���)��h���&������梷���� �Ǟ�m������)������^�����������v���O��zf������
