linux-kernel - Re: [PATCH RFC 0/2] of/unittest: Add reference count tests

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Message-ID: <CAMuHMdXUbD=4cOa-2Dwzhpz9vYVzjpewx4Z2tcMhccVyrJbVHg@mail.gmail.com>
Date:	Wed, 4 Feb 2015 18:08:37 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Rob Herring <robherring2@...il.com>
Cc:	Geert Uytterhoeven <geert+renesas@...der.be>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC 0/2] of/unittest: Add reference count tests

Hi Rob,

On Wed, Feb 4, 2015 at 5:14 PM, Rob Herring <robherring2@...il.com> wrote:
> On Fri, Jan 23, 2015 at 10:10 AM, Geert Uytterhoeven
> <geert+renesas@...der.be> wrote:
>> This patch series adds tests to detect reference count imbalances.
>> The tests use a fixed list of paths to devices nodes (required device
>> nodes in a minimal DTS, and device nodes present in unittest-data).
>> I considered scanning for all present device node instead, but these
>> are more likely to change while running the test.
>>
>> These tests are executed only if CONFIG_OF_DYNAMIC=y.
>>
>> Patches are against devicetree/next, with "[PATCH] of: Add missing
>> of_node_put() in of_find_node_by_path()" (or the alternative proposed
>> by Grant) applied.
>>
>> Note that it shows 44 failures, which I haven't investigated yet:
>
> Do you plan to?

Maybe. It doesn't have such a high priority in my task list...

> While this could find problems in the unittests or the core OF code,
> the vast majority of the problems are likely in the users and this
> doesn't help with those. This whole issue of ref counts has been
> discussed some and probably needs to be redesigned or instrumented in
> a way that users can validate. But then it is pretty low priority
> given that ref counts only matter on pseries.

I agree most issues are in the users.
However, I did find one issue in the core code.

Note that the reference counts may become more important in the future,
as OF_OVERLAY selects OF_DYNAMIC.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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