On Wed, 2017-07-05 at 10:56 -0400, Steven Rostedt wrote: > On Wed, 05 Jul 2017 07:50:28 -0700 > James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > On Wed, 2017-07-05 at 10:36 -0400, Steven Rostedt wrote: > > > > > > On Wed, 5 Jul 2017 15:33:41 +0100 > > > Mark Brown <broonie@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > > On Wed, Jul 05, 2017 at 04:06:07PM +0200, Greg KH wrote: > > > > > > > > > > > > > > > > > > > I don't mean to poo-poo the idea, but please realize that > > > > > around 75% of the kernel is hardware/arch support, so that > > > > > means that 75% of the changes/fixes deal with hardware things > > > > > (yes, change is in direct correlation to size of the codebase > > > > > in the tree, strange but true). > > > > > > > > Then add in all the fixes for concurrency/locking issues and so > > > > on that're hard to reliably reproduce as well... > > > > > > All tests should be run with lockdep enabled ;-) Which a > > > surprising few developers appear to do :-p > > > > Lockdep checks the locking hierarchies and makes assumptions about > > them which it then validates ... it doesn't tell you if the data > > you think > > We should probably look at adding infrastructure that helps in that. > RCU already has a lot of there to help know if data is being > protected by RCU or not. > > Hmm, maybe we could add a __rcu like type that we can associate > protected data with, where a config can associate access to a > variable with a lock being held? That's about 10x more complex than the releases/acquires/must_hold annotation, which we have fairly dismal coverage on. If you remember the hotplug annotations, which were a shining example: there's a limit of complexity before any annotation system simply becomes a make work tyranny. > > you're protecting was accessed outside the lock, which is the usual > > source of concurrency problems. In other words lockdep is useful > > but it's not a panacea. > > Still not an excuse to not have lockdep enabled during tests. OK, what makes you think lockdep isn't enabled? Since Kconfig is so complex, I usually use a distro config ... they have it enabled (or at least openSUSE does), so it's enabled for everything I do. James -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
