linux-kernel - Re: [PATCH] ARM: don't export unused return

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Message-ID: <CAMuHMdXk9sWBpYWC-X6V3rp2e0+f5ebdRFFXn8Heuy0qkLq0GQ@mail.gmail.com>
Date:   Wed, 13 Nov 2019 14:15:00 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Arnd Bergmann <arnd@...db.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Enrico Weigelt <info@...ux.net>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: don't export unused return_address()

Hi Russell,

On Wed, Nov 13, 2019 at 12:45 PM Russell King - ARM Linux admin
<linux@...linux.org.uk> wrote:
> On Wed, Nov 13, 2019 at 08:40:39PM +0900, Masahiro Yamada wrote:
> > On Tue, Oct 1, 2019 at 11:31 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > > On Fri, Sep 6, 2019 at 5:47 PM Arnd Bergmann <arnd@...db.de> wrote:
> > > > Without the frame pointer enabled, return_address() is an inline
> > > > function and does not need to be exported, as shown by this warning:
> > > >
> > > > WARNING: "return_address" [vmlinux] is a static EXPORT_SYMBOL_GPL
> > > >
> > > > Move the EXPORT_SYMBOL_GPL() into the #ifdef as well.
> > > >
> > > > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> > >
> > > Thanks for your patch!
> > >
> > > Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>
> > >
> > > > --- a/arch/arm/kernel/return_address.c
> > > > +++ b/arch/arm/kernel/return_address.c
> > > > @@ -53,6 +53,7 @@ void *return_address(unsigned int level)
> > > >                 return NULL;
> > > >  }
> > > >
> > >
> > > Checkpatch doesn't like the empty line above:
> > >
> > > WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
> > >
> > > > +EXPORT_SYMBOL_GPL(return_address);
> > > > +
> > > >  #endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
> > > >
> > > > -EXPORT_SYMBOL_GPL(return_address);

> > What has happened to this patch?
> >
> > I still see this warning.
>
> Simple - it got merged, it caused build regressions, it got dropped.
> A new version is pending me doing another round of patch merging.

I believe that was not Arnd's patch, but Ben Dooks' alternative solution[*]?

[*] Commit 0b0617e5a610fe12 ("ARM: 8918/1: only build return_address() if
    needed"), which I discovered in next-20191031 when checking if Arnd's
    patch was applied....


Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds