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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Fri, 17 May 2019 13:45:11 +0900
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Subject: Re: [PATCH v2] kbuild: check uniqueness of module names
To:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Cc:     Sam Ravnborg <sam@ravnborg.org>, Arnd Bergmann <arnd@arndb.de>,
        Greg KH <gregkh@linuxfoundation.org>,
        Jessica Yu <jeyu@kernel.org>,
        Lucas De Marchi <lucas.de.marchi@gmail.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Michael Schmitz <schmitzmic@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Rusty Russell <rusty@rustcorp.com.au>,
        Kees Cook <keescook@chromium.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, May 17, 2019 at 1:29 PM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> In the recent build test of linux-next, Stephen saw a build error
> caused by a broken .tmp_versions/*.mod file:
>
>   https://lkml.org/lkml/2019/5/13/991
>
> drivers/net/phy/asix.ko and drivers/net/usb/asix.ko have the same
> basename, and there is a race in generating .tmp_versions/asix.mod
>
> Kbuild has not checked this before, and it suddenly shows up with
> obscure error message when this kind of race occurs.
>
> Non-unique module names cause various sort of problems, but it is
> not trivial to catch them by eyes.
>
> Hence, this script.
>
> It checks not only real modules, but also built-in modules (i.e.
> controlled by tristate CONFIG option, but currently compiled with =y).
> Non-unique names for built-in modules also cause problems because
> /sys/modules/ would fall over.
>
> I tested allmodconfig on the latest kernel, and it detected the
> following:
>
> warning: same basename if the following are built as modules:
>   drivers/regulator/88pm800.ko
>   drivers/mfd/88pm800.ko
> warning: same basename if the following are built as modules:
>   drivers/gpu/drm/bridge/adv7511/adv7511.ko
>   drivers/media/i2c/adv7511.ko
> warning: same basename if the following are built as modules:
>   drivers/net/phy/asix.ko
>   drivers/net/usb/asix.ko
> warning: same basename if the following are built as modules:
>   fs/coda/coda.ko
>   drivers/media/platform/coda/coda.ko
> warning: same basename if the following are built as modules:
>   drivers/net/phy/realtek.ko
>   drivers/net/dsa/realtek.ko
>
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> ---


One more question popped up.

External modules are out of scope of the community,
but it is possible that people create an external module
that happens to have the same name as an upstream driver.

drivers/this/is/upstream/subsystem/foo.ko
/home/fred/my/own/external/module/foo.ko

Is modprobe confused in this case too?

Perhaps, checking for the M= build
might be good too...


-- 
Best Regards
Masahiro Yamada