linux-kernel - Re: [PATCH] of: provide of_platform

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 22 Jul 2013 00:44:27 +0100
From:	Grant Likely <grant.likely@...aro.org>
To:	Rob Herring <robherring2@...il.com>
Cc:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Rob Herring <rob.herring@...xeda.com>,
	Kishon Vijay Abraham I <kishon@...com>,
	George Cherian <george.cherian@...com>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	devicetree-discuss <devicetree-discuss@...ts.ozlabs.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Felipe Balbi <balbi@...com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Vivek Gautam <gautam.vivek@...sung.com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	Naveen Krishna Chatradhi <ch.naveen@...sung.com>,
	Roger Quadros <rogerq@...com>
Subject: Re: [PATCH] of: provide of_platform_unpopulate()

On Sun, Jul 21, 2013 at 9:48 PM, Rob Herring <robherring2@...il.com> wrote:
> On 07/21/2013 09:42 AM, Rob Herring wrote:
>> On 07/19/2013 01:14 PM, Sebastian Andrzej Siewior wrote:
>>> So I called of_platform_populate() on a device to get each child device
>>> probed and on rmmod and I need to reverse its doing. After a quick grep
>>> I did what others did as well and rmmod ended in:
>>>
>>> | Unable to handle kernel NULL pointer dereference at virtual address 00000018
>>> | PC is at release_resource+0x18/0x80
>>> | Process rmmod (pid: 2005, stack limit = 0xedc30238)
>>> | [<c003add0>] (release_resource+0x18/0x80) from [<c0300e08>] (platform_device_del+0x78/0xac)
>>> | [<c0300e08>] (platform_device_del+0x78/0xac) from [<c0301358>] (platform_device_unregister+0xc/0x18)
>>>
>>> The problem is that platform_device_del() "releases" each ressource in its
>>> tree. This does not work on platform_devices created by OF becuase they
>>> were never added via insert_resource(). As a consequence old->parent in
>>> __release_resource() is NULL and we explode while accessing ->child.
>>> So I either I do something completly wrong _or_ nobody here tested the
>>> rmmod path of their driver.
>>
>> Wouldn't the correct fix be to call insert_resource somehow? The problem
>> I have is that while of_platform_populate is all about parsing the DT
>> and creating devices, the removal side has nothing to do with DT. So
>> this should not be in the DT code. I think the core device code should
>> be able to handle removal if the device creation side is done correctly.
>>
>> It looks to me like of_device_add either needs to call
>> platform_device_add rather than device_add. I think the device name
>> setting in platform_device_add should be a nop. If not, a check that the
>> name is already set could be added.
>>
>
> BTW, it looks like Grant has attempted this already:

Yup, things broke badly. Unfortunately the of_platform_device and
platform_device history doesn't treat resources in the same way. I
would like to merge the code, but I haven't been able to figure out a
clean way to do it. Looks like we do need the unpopulate function.

g.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/