On Thu, 22 Jan 2015 15:49:59 -0600
, Suman Anna [off-list ref]
 wrote:

Hi Grant,

On 01/13/2015 05:04 PM, Suman Anna wrote:

quoted

On 01/13/2015 04:00 PM, Rob Herring wrote:

quoted

On Tue, Jan 13, 2015 at 3:25 PM, Suman Anna [off-list ref] wrote:

quoted

Hi Rob,

On 01/13/2015 02:38 PM, Rob Herring wrote:

quoted

On Wed, Jan 7, 2015 at 11:30 AM, Suman Anna [off-list ref] wrote:

quoted

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.

quoted

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

quoted

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.