On Wed, 25 Oct 2023 15:16:16 +0200
Geert Uytterhoeven <ge...@linux-m68k.org> wrote:
> Hi Adrian,
>
> On Wed, Oct 25, 2023 at 12:32 PM John Paul Adrian Glaubitz
> <glaub...@physik.fu-berlin.de> wrote:
> > On Wed, 2023-10-25 at 11:30 +0100, Mark Rutland wrote:
> > > On Wed, Oct 25, 2023 at 08:42:55AM +0900, Masami Hiramatsu wrote:
> > > > On Tue, 24 Oct 2023 16:08:12 +0100
> > > > Mark Rutland <mark.rutl...@arm.com> wrote:
> > > > > On Tue, Oct 24, 2023 at 11:52:54PM +0900, Masami Hiramatsu (Google)
> > > > > wrote:
> > > > > > From: Masami Hiramatsu (Google) <mhira...@kernel.org>
> > > > > >
> > > > > > Use generic_cmpxchg_local() for arch_cmpxchg_local() implementation
> > > > > > in SH architecture because it does not implement
> > > > > > arch_cmpxchg_local().
> > > > >
> > > > > I do not think this is correct.
> > > > >
> > > > > The implementation in <asm-generic/cmpxchg-local.h> is UP-only (and
> > > > > it only
> > > > > disables interrupts), whereas arch/sh can be built SMP. We should
> > > > > probably add
> > > > > some guards into <asm-generic/cmpxchg-local.h> for that as we have in
> > > > > <asm-generic/cmpxchg.h>.
> > > >
> > > > Isn't cmpxchg_local for the data which only needs to ensure to do
> > > > cmpxchg
> > > > on local CPU?
> > > > So I think it doesn't care about the other CPUs (IOW, it should not
> > > > touched by
> > > > other CPUs), so it only considers UP case. E.g. on x86,
> > > > arch_cmpxchg_local() is
> > > > defined as raw "cmpxchg" without lock prefix.
> > > >
> > > > #define __cmpxchg_local(ptr, old, new, size)
> > > > \
> > > > __raw_cmpxchg((ptr), (old), (new), (size), "")
> > > >
> > >
> > > Yes, you're right; sorry for the noise.
> > >
> > > For your original patch:
> > >
> > > Acked-by: Mark Rutland <mark.rutl...@arm.com>
> >
> > Geert, what's your opinion on this?
>
> While this looks OK on first sight (ARM includes the same file, even
> on SMP), it does not seem to work?
>
> For sh-allnoconfig, as reported by kernel test robot:
>
> $ make ARCH=sh CROSS_COMPILE=sh2-linux- allnoconfig lib/objpool.o
> lib/objpool.c: In function 'objpool_try_add_slot':
> ./include/linux/atomic/atomic-arch-fallback.h:384:27: error: implicit
> declaration of function 'arch_cmpxchg_local'; did you mean
> 'raw_cmpxchg_local'? [-Werror=implicit-function-declaration]
> 384 | #define raw_cmpxchg_local arch_cmpxchg_local
> | ^~~~~~~~~~~~~~~~~~
> ./include/linux/atomic/atomic-arch-fallback.h:392:16: note: in
> expansion of macro 'raw_cmpxchg_local'
> 392 | ___r = raw_cmpxchg_local((_ptr), ___o, (_new)); \
> | ^~~~~~~~~~~~~~~~~
> ./include/linux/atomic/atomic-instrumented.h:4980:9: note: in
> expansion of macro 'raw_try_cmpxchg_local'
> 4980 | raw_try_cmpxchg_local(__ai_ptr, __ai_oldp, __VA_ARGS__); \
> | ^~~~~~~~~~~~~~~~~~~~~
> lib/objpool.c:169:19: note: in expansion of macro 'try_cmpxchg_local'
> 169 | } while (!try_cmpxchg_local(&slot->tail, &tail, tail + 1));
> | ^~~~~~~~~~~~~~~~~
>
> For an SMP defconfig:
>
> $ make ARCH=sh CROSS_COMPILE=sh4-linux-gnu- sdk7786_defconfig lib/objpool.o
>
> ./include/linux/atomic/atomic-arch-fallback.h:384:27: error: implicit
> declaration of function ‘arch_cmpxchg_local’; did you mean
> ‘try_cmpxchg_local’? [-Werror=implicit-function-declaration]
> 384 | #define raw_cmpxchg_local arch_cmpxchg_local
> | ^~~~~~~~~~~~~~~~~~
> ./include/linux/atomic/atomic-arch-fallback.h:392:16: note: in
> expansion of macro ‘raw_cmpxchg_local’
> 392 | ___r = raw_cmpxchg_local((_ptr), ___o, (_new)); \
> | ^~~~~~~~~~~~~~~~~
> ./include/linux/atomic/atomic-instrumented.h:4980:9: note: in
> expansion of macro ‘raw_try_cmpxchg_local’
> 4980 | raw_try_cmpxchg_local(__ai_ptr, __ai_oldp, __VA_ARGS__); \
> | ^~~~~~~~~~~~~~~~~~~~~
> lib/objpool.c:169:19: note: in expansion of macro ‘try_cmpxchg_local’
> 169 | } while (!try_cmpxchg_local(&slot->tail, &tail, tail + 1));
> | ^~~~~~~~~~~~~~~~~
>
> Hiramatsu-san: do these build for you?
Thanks for pointing. I thought I just need to include the header file.
That's my fault.
Let me fix that.
Thank you!
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
> ge...@linux-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
--
Masami Hiramatsu (Google) <mhira...@kernel.org>
