Cc: Pekka Enberg <penberg@...>, Peter Zijlstra <a.p.zijlstra@...>, Dave Jones <davej@...>, Roland Dreier <rdreier@...>, Linus Torvalds <torvalds@...>, David Miller <davem@...>, <jeremy@...>, <hugh@...>, <mingo@...>, <akpm@...>, <linux-kernel@...>
On Mon, Aug 04, 2008 at 04:38:16PM -0700, Arjan van de Ven wrote:
I reported it to Peter. If you see David's email, I guess it can be
implied that I wasn't the only one aware that prove-locking made
certain systems non functional, I thought it was widespread knowledge
maybe not.
It's amazing that things seem to have improved on that side, it surely
gives me more confidence in prove-locking!
So let me understand better: your opinion is that all of lockdep is
useful, not just the AB BA detection?
By reading the source again after 11 months to me it still looks
check_deadlock() only has knowledge of the current context. It loops
over the task struct checking all the locks of the current task!
Combine the great feature that check_deadlock provides, with crashing
at boot, and I hope that better explains my feeling about
lockdep-prove-locking.
This check_deadlock() thing is the real core of my dislike of
prove-locking! The check_noncircular part I totally agree it's useful
now that I see it works differently than check_deadlock (when I read
it last time I thought it worked the same as check_deadlock).
check_noncircular being useful doesn't automatically make
check_deadlock useful.
And incidentally it's exactly this check_deadlock part that is
trapping on my code and that is now requiring silly changes to the
common code (the ones I did) or to make the common code even more
complex (what Peter is planning I guess).
--
