From: Michael Bringmann <mwb@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
Frank Rowand <frowand.list@gmail.com>,
Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org, tlfalcon@linux.vnet.ibm.com,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
minkim@us.ibm.com, Tyrel Datwyler <tyreld@linux.vnet.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v03] powerpc/mobility: Fix node detach/rename problem
Date: Fri, 14 Dec 2018 15:58:49 -0600 [thread overview]
Message-ID: <90fba2b5-139d-ec05-5708-0f0b656b142a@linux.vnet.ibm.com> (raw)
In-Reply-To: <877egew2ur.fsf@concordia.ellerman.id.au>
On 12/12/2018 08:57 PM, Michael Ellerman wrote:
> Frank Rowand <frowand.list@gmail.com> writes:
>> On 12/11/18 8:07 AM, Rob Herring wrote:
>>> On Tue, Dec 11, 2018 at 7:29 AM Michael Ellerman <mpe@ellerman.id.au> wrote:
> ...
>>>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>>>> index 09692c9b32a7..d8e4534c0686 100644
>>>> --- a/drivers/of/base.c
>>>> +++ b/drivers/of/base.c
>>>> @@ -1190,6 +1190,10 @@ struct device_node *of_find_node_by_phandle(phandle handle)
>>>> if (phandle_cache[masked_handle] &&
>>>> handle == phandle_cache[masked_handle]->phandle)
>>>> np = phandle_cache[masked_handle];
>>>> +
>>>> + /* If we find a detached node, remove it */
>>>> + if (of_node_check_flag(np, OF_DETACHED))
>>>> + np = phandle_cache[masked_handle] = NULL;
>>
>> The bug you found exposes a couple of different issues, a little bit
>> deeper than the proposed fix. I'll work on a fuller fix tonight or
>> tomorrow.
>
> OK thanks.
>
>>> I'm wondering if we should explicitly remove the node from the cache
>>> when we set OF_DETACHED. Otherwise, it could be possible that the node
>>> pointer has been freed already. Or maybe we need both?
>>
>> Yes, it should be explicitly removed. I may also add in a paranoia check in
>> of_find_node_by_phandle().
>
> That seems best to me.
I agree that we should do both.
>
> cheers
Michael
--
Michael W. Bringmann
Linux I/O, Networking and Security Development
IBM Corporation
Tie-Line 363-5196
External: (512) 286-5196
Cell: (512) 466-0650
mwb@linux.vnet.ibm.com
next prev parent reply other threads:[~2018-12-14 21:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <a2d46622-a957-dffe-04d1-8087bbf0f8b5@linux.vnet.ibm.com>
2018-12-11 13:29 ` [PATCH v03] powerpc/mobility: Fix node detach/rename problem Michael Ellerman
2018-12-11 15:26 ` Michael Bringmann
2018-12-11 16:07 ` Rob Herring
2018-12-12 22:00 ` Frank Rowand
2018-12-13 2:57 ` Michael Ellerman
2018-12-14 21:58 ` Michael Bringmann [this message]
2018-12-13 2:56 ` Michael Ellerman
2018-12-11 16:43 ` Michael Bringmann
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