linux-kernel - Re: [PATCH 16/27] modpost: make multiple export error

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Date:   Mon, 25 Apr 2022 11:48:00 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michal Marek <michal.lkml@...kovi.net>
Subject: Re: [PATCH 16/27] modpost: make multiple export error

On Sun, Apr 24, 2022 at 12:09 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> This is currently a warning, but I think modpost should stop building
> in this case.
>
> If the same symbol is exported multiple times and we let it keep going,
> the sanity check becomes difficult.
>
> Only the legitimate case is that an external module overrides the
> corresponding in-tree module to provide a different implementation
> with the same interface.

Could the same module export a weak version of a symbol, and a strong one?

Can kernel modules override in-kernel strong symbols?

>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
>
>  scripts/mod/modpost.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 14044cd94aaa..73f0b98e3b5a 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -411,9 +411,9 @@ static struct symbol *sym_add_exported(const char *name, struct module *mod,
>                 list_add_tail(&s->list, &mod->exported_symbols);
>         } else if (!external_module || s->module->is_vmlinux ||
>                    s->module == mod) {
> -               warn("%s: '%s' exported twice. Previous export was in %s%s\n",
> -                    mod->name, name, s->module->name,
> -                    s->module->is_vmlinux ? "" : ".ko");
> +               error("%s: '%s' exported twice. Previous export was in %s%s\n",
> +                     mod->name, name, s->module->name,
> +                     s->module->is_vmlinux ? "" : ".ko");
>                 return s;
>         }
>
> --
> 2.32.0
>


-- 
Thanks,
~Nick Desaulniers