On Thu, 22 Jan 2015 15:49:59 -0600 , Suman Anna <s-anna@xxxxxx> wrote: > Hi Grant, > > On 01/13/2015 05:04 PM, Suman Anna wrote: > > On 01/13/2015 04:00 PM, Rob Herring wrote: > >> On Tue, Jan 13, 2015 at 3:25 PM, Suman Anna <s-anna@xxxxxx> wrote: > >>> Hi Rob, > >>> > >>> On 01/13/2015 02:38 PM, Rob Herring wrote: > >>>> On Wed, Jan 7, 2015 at 11:30 AM, Suman Anna <s-anna@xxxxxx> wrote: > >>>>> Drivers can use of_platform_populate() to create platform devices > >>>>> for children of the device main node, and a complementary API > >>>>> of_platform_depopulate() is provided to delete these child platform > >>>>> devices. The of_platform_depopulate() leverages the platform API > >>>>> for performing the cleanup of these devices. > >>>>> > >>>>> The platform device resources are managed differently between > >>>>> of_device_add and platform_device_add, and this asymmetry causes > >>>>> a kernel oops in platform_device_del during removal of the resources. > >>>>> Manage the platform device resources similar to platform_device_add > >>>>> to fix this kernel oops. > >>>> > >>>> This is a known issue and has been attempted to be fixed before (I > >>>> believe there is a revert in mainline). The problem is there are known > >>>> devicetrees which have overlapping resources and they will break with > >>>> your change. > >>> > >>> Are you referring to 02bbde7849e6 (Revert "of: use > >>> platform_device_add")? > >> > >> I believe that's the one. > >> > >>> That one seems to be in registration path, and > >>> this crash is in the unregistration path. If so, to fix the crash, > >>> should we be skipping the release_resource() for now in > >>> platform_device_del for DT nodes, or replace platform_device_unregister > >>> with of_device_unregister in of_platform_device_destroy()? > >> > >> IIRC, the problem is inserting a resource twice on add from 2 > >> different nodes, not the removal path. Perhaps we could make a > >> collision non-fatal for in the DT case. > > > > We may be talking two different things here, I understand that this > > patch would create an issue with inserting a resource twice in the > > devicetrees with overlapping resources (just like the commit that was > > reverted above), but the crash is on devices with resources whose > > parent, child, sibling pointers have never been initialized (the > > of_device_add path does not touch these at all), and get dereferenced in > > platform_device_del()->release_resource(). See the following that has a > > better explanation [1]. > > > > regards > > Suman > > > > [1] > > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/274412.html > > > > > >> Grant may have some ideas on > >> what's needed here. > > Ping, any suggestions here? Do we ought to replace > platform_device_unregister() with of_device_unregister() similar to the > approach taken in 02bbde7849e6 (Revert "of: use platform_device_add")? Hi Suman, Yes, I think the solution to both problems is to create an of_device_unregister() function. It's not the prettiest thing, but I think it is for the best. g. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
