linux-kernel - Re: [PATCH 4/4] modpost: do not set ->preloaded for symbols from Module.symvers

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Message-ID: <CAPcyv4gFO=4EmObucuYyPNCS91y1H7d-M=0LebBK72YuD=ekNQ@mail.gmail.com>
Date:   Sun, 3 Nov 2019 22:43:31 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Jeff Moyer <jmoyer@...hat.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>
Subject: Re: [PATCH 4/4] modpost: do not set ->preloaded for symbols from Module.symvers

On Sun, Nov 3, 2019 at 7:12 PM Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
>
> On Sat, Nov 2, 2019 at 3:52 AM Jeff Moyer <jmoyer@...hat.com> wrote:
> >
> > Masahiro Yamada <yamada.masahiro@...ionext.com> writes:
> >
> > > On Fri, Nov 1, 2019 at 1:51 AM Jeff Moyer <jmoyer@...hat.com> wrote:
> > >>
> > >> Masahiro Yamada <yamada.masahiro@...ionext.com> writes:
> > >>
> > >> > Now that there is no overwrap between symbols from ELF files and
> > >> > ones from Module.symvers.
> > >> >
> > >> > So, the 'exported twice' warning should be reported irrespective
> > >> > of where the symbol in question came from. Only the exceptional case
> > >> > is when __crc_<sym> symbol appears before __ksymtab_<sym>. This
> > >> > typically occurs for EXPORT_SYMBOL in .S files.
> > >>
> > >> Hi, Masahiro,
> > >>
> > >> After apply this patch, I get the following modpost warnings when doing:
> > >>
> > >> $ make M=tools/tesing/nvdimm
> > >> ...
> > >>   Building modules, stage 2.
> > >>   MODPOST 12 modules
> > >> WARNING: tools/testing/nvdimm/libnvdimm: 'nvdimm_bus_lock' exported
> > >> twice. Previous export was in drivers/nvdimm/libnvdimm.ko
> > >> WARNING: tools/testing/nvdimm/libnvdimm: 'nvdimm_bus_unlock'
> > >> exported twice. Previous export was in drivers/nvdimm/libnvdimm.ko
> > >> WARNING: tools/testing/nvdimm/libnvdimm: 'is_nvdimm_bus_locked'
> > >> exported twice. Previous export was in drivers/nvdimm/libnvdimm.ko
> > >> WARNING: tools/testing/nvdimm/libnvdimm: 'devm_nvdimm_memremap'
> > >> exported twice. Previous export was in drivers/nvdimm/libnvdimm.ko
> > >> WARNING: tools/testing/nvdimm/libnvdimm: 'nd_fletcher64' exported twice. Previous export was in drivers/nvdimm/libnvdimm.ko
> > >> WARNING: tools/testing/nvdimm/libnvdimm: 'to_nd_desc' exported twice. Previous export was in drivers/nvdimm/libnvdimm.ko
> > >> WARNING: tools/testing/nvdimm/libnvdimm: 'to_nvdimm_bus_dev'
> > >> exported twice. Previous export was in drivers/nvdimm/libnvdimm.ko
> > >> ...
> > >>
> > >> There are a lot of these warnings.  :)
> > >
> > > These warnings are correct since
> > > drivers/nvdimm/Makefile and
> > > tools/testing/nvdimm/Kbuild
> > > compile the same files.
> >
> > Yeah, but that's by design.  Is there a way to silence these warnings?
> >
> > -Jeff
> >
>
> "rm -f Module.symvers; make M=tools/testing/nvdimm" ?
>
> I'd like the _design_ fixed though.

This design is deliberate. The goal is to re-build the typical nvdimm
modules, but link them against mocked version of core kernel symbols.
This enables the nvdimm unit tests which have been there for years and
pre-date Kunit. That said, deleting Module.symvers seems a simple
enough workaround.