linux-kernel - Re: [PATCH v3 13/18] of: overlay: check prevents multiple fragments touching same property

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Date:   Mon, 15 Oct 2018 12:30:11 -0700
From:   Frank Rowand <frowand.list@...il.com>
To:     Joe Perches <joe@...ches.com>, Rob Herring <robh+dt@...nel.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Alan Tull <atull@...nel.org>, Moritz Fischer <mdf@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        devicetree@...r.kernel.org, linux-fpga@...r.kernel.org
Subject: Re: [PATCH v3 13/18] of: overlay: check prevents multiple fragments
 touching same property

On 10/14/18 20:21, Frank Rowand wrote:
> On 10/14/18 18:55, Joe Perches wrote:
>> On Sun, 2018-10-14 at 18:52 -0700, Frank Rowand wrote:
>>> On 10/14/18 18:06, Joe Perches wrote:
>>>> On Sun, 2018-10-14 at 17:24 -0700, frowand.list@...il.com wrote:
>>>>> From: Frank Rowand <frank.rowand@...y.com>
>>>>>
>>>>> Add test case of two fragments updating the same property.  After
>>>>> adding the test case, the system hangs at end of boot, after
>>>>> after slub stack dumps from kfree() in crypto modprobe code.
>> []
>>>> I think this is worse performance than before.
>>>>
>>>> This now walks all entries when before it would
>>>> return -EINVAL directly when it found a match.
>>>
>>> Yes, it is worse performance, but that is OK.
>>>
>>> This is a check that is done when a devicetree overlay is applied.
>>> If an error occurs then that means that the overlay was incorrectly
>>> specified.  The file drivers/of/unittest-data/overlay_bad_add_dup_prop.dts
>>> in this patch provides an example of how a bad overlay can be created.
>>>
>>> Once an error was detected, the check could return immediately, or it
>>> could continue to give a complete list of detected errors.  I chose to
>>> give the complete list of detected errors.
>>
>> Swell.  Please describe that in the commit message.
> 
> If a version 4 of the series is created I will update the commit
> message.  As a stand alone item I do not think it is worth a
> new version.

And there will be a version 4, so I will update the commit message.

-Frank