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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 12 Jan 2022 13:08:24 +0100
Message-ID: <CAK8P3a3FgHQ+w+Sj00yOERRLWfVhx7NYsGJ1NBAXQ0=is3G=Kg@mail.gmail.com>
Subject: Re: [PATCH 4/5] uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h
To:     Jeff Layton <jlayton@kernel.org>
Cc:     Arnd Bergmann <arnd@arndb.de>, Christoph Hellwig <hch@lst.de>,
        Guo Ren <guoren@kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
        Parisc List <linux-parisc@vger.kernel.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        linux-s390 <linux-s390@vger.kernel.org>,
        sparclinux <sparclinux@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        "J. Bruce Fields" <bfields@fieldses.org>
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On Wed, Jan 12, 2022 at 12:15 PM Jeff Layton <jlayton@kernel.org> wrote:
> On Wed, 2022-01-12 at 09:28 +0100, Arnd Bergmann wrote:
> > On Wed, Jan 12, 2022 at 8:56 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > Exactly, that is the tradeoff, which is why I'd like the flock maintainers
> > to say which way they prefer. We can either do it more correctly (hiding
> > the constants from user space when they are not usable), or with less
> > change (removing the incorrect #ifdef). Either way sounds reasonable
> > to me, I mainly care that this is explained in the changelog and that the
> > maintainers are aware of the two options.
> >
>
> I don't have a strong opinion here. If we were taking symbols away that
> were previously visible to userland it would be one thing, but since
> we're just adding symbols that may not have been there before, this
> seems less likely to break anything.

Changing

#ifndef CONFIG_64BIT

to

#if __BITS_PER_LONG==32 || defined(__KERNEL__),

would take symbols away, since the CONFIG_64BIT macro is never
set in user space.

> I probably lean toward Christoph's original solution instead of keeping
> the conditional definitions. It's hard to imagine there are many
> programs that care whether these other symbols are defined or not.
>
> You can add this to the original patch:
>
> Acked-by: Jeff Layton <jlayton@kernel.org>

Sounds good, thanks

         Arnd