On Fri, Jan 18, 2019 at 11:58:54AM -0800, Dave Hansen wrote: > On 1/16/19 11:16 AM, Jerome Glisse wrote: > >> We *could* also simply truncate the existing top-level > >> "Persistent Memory" resource and take over the released address > >> space. But, this means that if we ever decide to hot-unplug the > >> "RAM" and give it back, we need to recreate the original setup, > >> which may mean going back to the BIOS tables. > >> > >> This should have no real effect on the existing collision > >> detection because the areas that truly conflict should be marked > >> IORESOURCE_BUSY. > > > > Still i am worrying that this might allow device private to register > > itself as a child of some un-busy resource as this patch obviously > > change the behavior of register_memory_resource() > > > > What about instead explicitly providing parent resource to add_memory() > > and then to register_memory_resource() so if it is provided as an > > argument (!NULL) then you can __request_region(arg_res, ...) otherwise > > you keep existing code intact ? > > We don't have the locking to do this, do we? For instance, all the > locking is done below register_memory_resource(), so any previous > resource lookup is invalid by the time we get to register_memory_resource(). Yeah you are right, maybe just a bool then ? bool as_child Cheers, Jérôme
