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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Sun, 7 Oct 2018 06:58:08 +0900
Message-ID: <CAK7LNAT5h+Rku7DbD+kHGv7Kgk8FfuX4wwL_pwNOLSJbqw99MA@mail.gmail.com>
Subject: Re: [PATCH] kbuild: fix kernel/bounds.c 'W=1' warning
To:     miguel.ojeda.sandonis@gmail.com
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        kieran.bingham+renesas@ideasonboard.com,
        stable <stable@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
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Hi Miguel,


On Sun, Oct 7, 2018 at 6:18 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Fri, Oct 5, 2018 at 10:35 AM Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > Building any configuration with 'make W=3D1' produces a warning:
> >
> > kernel/bounds.c:16:6: warnign: no previous prototype for 'foo' [-Wmissi=
ng-prototypes]
> >
> > When also passing -Werror, this prevents us from building any
> > other files. Nobody ever calls the function, but we can't make
> > it 'static' either since we want the compiler output.
> >
> > Calling it 'main' instead however avoids the warning, because gcc
> > does not insist on having a declaration for main.
>
> I think marking the function as static __used should do the trick and
> would be less confusing.


I tried __used, but I still see the warning.


masahiro@grover:~/ref/linux$ git diff
diff --git a/kernel/bounds.c b/kernel/bounds.c
index c373e88..aee0101 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -13,7 +13,7 @@
 #include <linux/log2.h>
 #include <linux/spinlock_types.h>

-void foo(void)
+void __used foo(void)
 {
        /* The enum constants to put into include/generated/bounds.h */
        DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS);
masahiro@grover:~/ref/linux$ make W=3D1  prepare
  CC      kernel/bounds.s
kernel/bounds.c:16:13: warning: no previous prototype for =E2=80=98foo=E2=
=80=99
[-Wmissing-prototypes]
 void __used foo(void)
             ^
  CC      arch/x86/kernel/asm-offsets.s


--=20
Best Regards
Masahiro Yamada