On Thu, 27 Nov 2014, Heiko Carstens wrote: > On Thu, Nov 27, 2014 at 09:03:01AM +0100, David Hildenbrand wrote: > > > Code like > > > spin_lock(&lock); > > > if (copy_to_user(...)) > > > rc = ... > > > spin_unlock(&lock); > > > really *should* generate warnings like it did before. > > > > > > And *only* code like > > > spin_lock(&lock); > > > > Is only code like this valid or also with the spin_lock() dropped? > > (e.g. the access in patch1 if I remember correctly) > > > > So should page_fault_disable() increment the pagefault counter and the preempt > > counter or only the first one? > > Given that a sequence like > > page_fault_disable(); > if (copy_to_user(...)) > rc = ... > page_fault_enable(); > > is correct code right now I think page_fault_disable() should increase both. > No need for surprising semantic changes. OTOH, there is no reason why we need to disable preemption over that page_fault_disabled() region. There are code pathes which really do not require to disable preemption for that. We have that seperated in preempt-rt for obvious reasons and IIRC Peter Zijlstra tried to distangle it in mainline some time ago. I forgot why that never got merged. We tie way too much stuff on the preemption count already, which is a mightmare because we have no clear distinction of protection scopes. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
