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?
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
