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Subject: Re: [PATCH v2 2/2] of: __of_detach_node() - remove node from phandle
 cache
To:     Rob Herring <robh+dt@kernel.org>
Cc:     Michael Ellerman <mpe@ellerman.id.au>, mwb@linux.vnet.ibm.com,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Tyrel Datwyler <tyreld@linux.vnet.ibm.com>,
        tlfalcon@linux.vnet.ibm.com, minkim@us.ibm.com,
        devicetree@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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 <CAL_JsqLjc-tWYOT7ga4oAsgx=rpcWX6_cj80pih-kt=KbFVV=w@mail.gmail.com>
From:   Frank Rowand <frowand.list@gmail.com>
Message-ID: <893d9327-4353-066d-2efa-414a3db4c282@gmail.com>
Date:   Tue, 18 Dec 2018 12:09:03 -0800
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On 12/18/18 12:01 PM, Rob Herring wrote:
> On Tue, Dec 18, 2018 at 12:57 PM Frank Rowand <frowand.list@gmail.com> wrote:
>>
>> On 12/17/18 2:52 AM, Michael Ellerman wrote:
>>> Hi Frank,
>>>
>>> frowand.list@gmail.com writes:
>>>> From: Frank Rowand <frank.rowand@sony.com>
>>>>
>>>> Non-overlay dynamic devicetree node removal may leave the node in
>>>> the phandle cache.  Subsequent calls to of_find_node_by_phandle()
>>>> will incorrectly find the stale entry.  Remove the node from the
>>>> cache.
>>>>
>>>> Add paranoia checks in of_find_node_by_phandle() as a second level
>>>> of defense (do not return cached node if detached, do not add node
>>>> to cache if detached).
>>>>
>>>> Reported-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
>>>> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
>>>> ---
>>>
>>> Similarly here can we add:
>>>
>>> Fixes: 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()")
>>
>> Yes, thanks.
>>
>>
>>> Cc: stable@vger.kernel.org # v4.17+
>>
>> Nope, 0b3ce78e90fc does not belong in stable (it is a feature, not a bug
>> fix).  So the bug will not be in stable.
> 
> 0b3ce78e90fc landed in v4.17, so Michael's line above is correct.
> Annotating it with 4.17 only saves Greg from trying and then emailing
> us to backport this patch as it wouldn't apply.

Thanks for the correction.  I was both under-thinking and over-thinking,
ending up with an incorrect answer.

Can you add the Cc: to version 3 patch comments (both 1/2 and 2/2) or do
you want me to re-spin?

-Frank

> 
> Rob
>