linux-kernel - Re: [PATCH v2] modpost: move the namespace field in Module.symvers last

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Date:   Tue, 31 Mar 2020 15:09:27 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Jessica Yu <jeyu@...nel.org>
Cc:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Matthias Maennich <maennich@...gle.com>,
        Lucas De Marchi <lucas.de.marchi@...il.com>,
        stable <stable@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] modpost: move the namespace field in Module.symvers last

On Tue, Mar 31, 2020 at 2:58 AM Jessica Yu <jeyu@...nel.org> wrote:
> +++ John Stultz [30/03/20 23:25 -0700]:
> >On Mon, Mar 30, 2020 at 10:49 PM John Stultz <john.stultz@...aro.org> wrote:
> >> The only difference I can find is that the Module.symvers in the
> >> external module project doesn't seem to have a tab at the end of each
> >> line (where as Module.symvers for the kernel - which doesn't seem to
> >> have any namespace names - does).
> >>
> >> Is there something I need to tweak on the external Kbuild to get
> >> Module.symvers to be generated properly (with the empty tab at the
> >> end) for this new change?
> >> Or does the parser need to be a bit more flexible?
> >>
> >
> >One extra clue on this: I noticed the external module Makefile had
> >KBUILD_EXTRA_SYMBOLS="$(EXTRA_SYMBOLS)"  in the $(MAKE) string, where
> >EXTRA_SYMBOLS pointed to some files that no longer exist.  I removed
> >the KBUILD_EXTRA_SYMBOLS= argument, and magically, the generated
> >Module.symvers now had tabs at the end of each line.
> >
> >I wonder if there some path in the KBUILD_EXTRA_SYMBOLS= handling that
> >isn't generating the output in the same way?
>
> I'm afraid we're going to need some specifics on reproducing this
> issue. Could you provide a reproducer or steps on how to reproduce? I
> have not been able to trigger this problem even with
> KBUILD_EXTRA_SYMBOLS pointing to an invalid path (I also tested with
> valid paths).
>
> I tested with a skeleton external module that exports two functions,
> one with a namespace and one without. I built this module against the
> latest v5.6 kernel. The generated Module.symvers was correct - the
> namespaced function had the namespace at the end and the other
> function without a namespace had a tab at the end.
>
> I also tested with two external modules, one with a symbol dependency
> on the other, so KBUILD_EXTRA_SYMBOLS usage is required here. The
> generated Module.symvers was also correct here.
>
> The only advice I can offer at this time is that all external modules
> must be built against the new kernel to generate a correctly formated
> Module.symvers file. If you have any KBUILD_EXTRA_SYMBOLS pointing to
> an outdated Module.symvers file for example, you will see the "FATAL:
> parse error in symbol dump file" error.

Well, my apologies.  :(  In the light of day, this isn't reproducing
anymore. I'm a bit at a loss as to why I was tripping over it so
regularly before, but I suspect something in the build is leaving a
stale Modules.symvers around from before this patch landed.

Terribly sorry for the noise.

thanks
-john