linux-kernel - Re: [PATCH] modpost: fix static EXPORT

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Date:   Tue, 24 Sep 2019 14:15:12 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kbuild@...r.kernel.org
Cc:     Denis Efremov <efremov@...ux.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] modpost: fix static EXPORT_SYMBOL warnings for UML build

On Tue, 2019-09-24 at 21:07 +0900, Masahiro Yamada wrote:
> Johannes Berg reports lots of modpost warnings on ARCH=um builds:
> 
> WARNING: "rename" [vmlinux] is a static EXPORT_SYMBOL
> [snip]
> WARNING: "__stack_smash_handler" [vmlinux] is a static EXPORT_SYMBOL
> 
> When you run "make", the modpost is run twice; before linking vmlinux,
> and before building modules. All the warnings above are from the second
> modpost.
> 
> The offending symbols are defined not in vmlinux, but in the C library.
> The first modpost is run against the relocatable vmlinux.o, and those
> warnings are nicely suppressed because the SH_UNDEF entries from the
> symbol table clear the ->is_static flag.
> 
> The second modpost is run against the executable vmlinux (+ modules),
> where those symbols have been resolved, but the definitions do not
> exist.
> 
> This commit fixes it in a straight forward way. Suppress the static
> EXPORT_SYMBOL warnings from "vmlinux".

Yep, that fixes it.

Tested-by: Johannes Berg <johannes@...solutions.net>

Thanks!

johannes