Re: [PATCH] Revert "asm-generic: Remove unneeded __ARCH_WANT_SYS_LLSEEK macro"

On Fri, Aug 30, 2019 at 09:54:43PM +0200, Arnd Bergmann wrote:

quoted

-#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.