Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756579AbaDPVdr (ORCPT ); Wed, 16 Apr 2014 17:33:47 -0400 Received: from mail-ve0-f177.google.com ([209.85.128.177]:64766 "EHLO mail-ve0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751390AbaDPVdp (ORCPT ); Wed, 16 Apr 2014 17:33:45 -0400 MIME-Version: 1.0 In-Reply-To: References: <1395179766-31575-1-git-send-email-pantelis.antoniou@konsulko.com> Date: Wed, 16 Apr 2014 16:33:44 -0500 Message-ID: Subject: Re: [PATCH v3 0/7] Introducing (yet again) Device Tree Overlays From: Rob Herring To: delicious quinoa Cc: Pantelis Antoniou , Grant Likely , Stephen Warren , Matt Porter , Koen Kooi , Alison Chaiken , Dinh Nguyen , Jan Lubbe , Alexander Sverdlin , Michael Stickel , Guenter Roeck , Dirk Behme , Sascha Hauer , Michael Bohan , Ionut Nicu , Michal Simek , Matt Ranostay , "devicetree@vger.kernel.org" , linux-kernel , Pete Popov , Dan Malek , Georgi Vlaev Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 16, 2014 at 4:23 PM, delicious quinoa wrote: > On Thu, Apr 3, 2014 at 3:40 PM, delicious quinoa > wrote: >> On Fri, Mar 28, 2014 at 1:27 PM, delicious quinoa >> wrote: >>> On Tue, Mar 18, 2014 at 4:55 PM, Pantelis Antoniou >>> wrote: >>>> The following patchset introduces Device Tree overlays, a method >>>> of dynamically altering the kernel's live Device Tree, along with >>>> a generic interface to use it in a board agnostic manner. [snip] >>> I can get a NULL pointer when I apply and remove an overlay and the >>> conditions are right. The overlay applies correctly. The crash is >>> when I do the rmdir. My overlay is: >>> >>> /dts-v1/; >>> /plugin/; >>> / { >>> fragment@0 { >>> target-path="/soc"; >>> __overlay__ { >>> #address-cells = <1>; >>> #size-cells = <1>; >>> agpio0: agpio0 { >>> compatible = "altr,pio-1.0"; >>> reg = <0xff210040 0x10>; >> >> Added some printks and got a bit further with debug. If I leave this >> as-is, the platform device has 2 resources. We get the NULL pointer in >> __release_resource() when releasing the first one (reg). If I remove >> this one line ('reg =') the crash goes away. So in this case, we are >> ok when releasing an irq resource but get a NULL pointer when removing >> a reg resource. Don't know why at this point. > > The crash is confirmed on v4 patches as well. The immediate cause of the crash: > > static int __release_resource(struct resource *old) > { > struct resource *tmp, **p; > > p = &old->parent->child; > for (;;) { > tmp = *p; <===kablooey > ... > > when __release_resource() is called for the reg resource, it does 'p = > &olde->parent->child' and then crashes when it does 'tmp = *p'. > > Root cause: It appears that there isn't any code in drivers/of/ that > eventually calls __request_resource() or __insert_resource() so the > resource's parents/sibling pointers are never initialized. Maybe I'm > missing some patches or something. It's probably related to this issue: https://groups.google.com/forum/#!topic/fa.linux.kernel/CTx1ReiOjnQ http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg63678.html Rob -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/