On Tue, 24 Oct 2023 16:08:12 +0100 Mark Rutland <[email protected]> wrote:
> On Tue, Oct 24, 2023 at 11:52:54PM +0900, Masami Hiramatsu (Google) wrote: > > From: Masami Hiramatsu (Google) <[email protected]> > > > > 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), "") Thank you, > > I think the right thing to do here is to define arch_cmpxchg_local() in terms > of arch_cmpxchg(), i.e. at the bottom of arch/sh's <asm/cmpxchg.h> add: > > #define arch_cmpxchg_local arch_cmpxchg > > Mark. > > > > > Reported-by: kernel test robot <[email protected]> > > Closes: > > https://lore.kernel.org/oe-kbuild-all/[email protected]/ > > Signed-off-by: Masami Hiramatsu (Google) <[email protected]> > > --- > > arch/sh/include/asm/cmpxchg.h | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/sh/include/asm/cmpxchg.h b/arch/sh/include/asm/cmpxchg.h > > index 288f6f38d98f..e920e61fb817 100644 > > --- a/arch/sh/include/asm/cmpxchg.h > > +++ b/arch/sh/include/asm/cmpxchg.h > > @@ -71,4 +71,6 @@ static inline unsigned long __cmpxchg(volatile void * > > ptr, unsigned long old, > > (unsigned long)_n_, sizeof(*(ptr))); \ > > }) > > > > +#include <asm-generic/cmpxchg-local.h> > > + > > #endif /* __ASM_SH_CMPXCHG_H */ > > -- Masami Hiramatsu (Google) <[email protected]>
