From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] Revert "asm-generic: Remove unneeded
 __ARCH_WANT_SYS_LLSEEK macro"
Date: Sat, 31 Aug 2019 01:38:49 -0700
Message-ID: <20190831083849.GA24644@infradead.org>
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To: Arnd Bergmann <arnd@arndb.de>
Cc: Rich Felker <dalias@libc.org>, Linux-sh list <linux-sh@vger.kernel.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Heiko Carstens <heiko.carstens@de.ibm.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, "James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>, Max Filippov <jcmvbkbc@gmail.com>, Guo Ren <guoren@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, sparclinux <sparclinux@vger.kernel.org>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Will Deacon <will@kernel.org>, linux-arch <linux-arch@vger.kernel.org>, linux-s390 <linux-s390@vger.kernel.org>, Yoshinori Sato <ysato@users.sourceforge.jp>, Michael Ellerman <mpe@ellerman.id.au>, Helge Deller <deller@gmx.de>, the arch/x86 maintainers <x86@kernel.org>, Russell King <linux@armlinux.org.uk>, Christian Borntraeger <borntraeger@de.ibm.com>, Ingo Molnar <mingo@redhat.com>, Geert
List-Id: linux-arch.vger.kernel.org

On Fri, Aug 30, 2019 at 09:54:43PM +0200, Arnd Bergmann wrote:
> > -#if !defined(CONFIG_64BIT) || defined(CONFIG_COMPAT)
> > +#ifdef __ARCH_WANT_SYS_LLSEEK
> >  SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
> >                 unsigned long, offset_low, loff_t __user *, result,
> >                 unsigned int, whence)
> 
> However, only reverting the patch will now break all newly added
> 32-bit architectures that don't define __ARCH_WANT_SYS_LLSEEK:
> at least nds32 and riscv32 come to mind, not sure if there is another.
> 
> I think the easiest way however would be to combine the two checks
> above and make it
> 
> #if !defined(CONFIG_64BIT) || defined(CONFIG_COMPAT) ||
> defined(__ARCH_WANT_SYS_LLSEEK)
> 
> and then only set __ARCH_WANT_SYS_LLSEEK for powerpc.

I'd much rather introduce a CONFIG_SYS_LLSEEK Kconfig symbol, selected
by CONFIG_64BIT and CONFIG_COMPAT by default, plus manually by powerpc.