Re: [PATCH 5/6] sh: Emulate two-byte cmpxchg

[John Paul Adrian Glaubitz]

Hi Bradley,

On Fri, 2026-09-11 at 19:25 +0000, Bradley Morgan wrote:
> SH has no byte or halfword atomic memory operations, so the
> __cmpxchg() switch routes case 1 through cmpxchg_emu_u8() and
> lets case 2 fall through to __cmpxchg_called_with_bad_pointer(),
> which is declared but never defined, so a two-byte cmpxchg()
> fails at link time. Route case 2 through the new cmpxchg_emu_u16().
> 
> Signed-off-by: Bradley Morgan <brads@xxxxxxxxxxxxxx>
> ---
>  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 1e5dc5ccf7bf..477d3025a441 100644
> --- a/arch/sh/include/asm/cmpxchg.h
> +++ b/arch/sh/include/asm/cmpxchg.h
> @@ -59,6 +59,8 @@ static inline unsigned long __cmpxchg(volatile void * ptr, unsigned long old,
>  	switch (size) {
>  	case 1:
>  		return cmpxchg_emu_u8(ptr, old, new);
> +	case 2:
> +		return cmpxchg_emu_u16(ptr, old, new);
>  	case 4:
>  		return __cmpxchg_u32(ptr, old, new);
>  	}

Odd, I thought this series was merged long time ago. Was there anything holding it back?

Either way:

Acked-by: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>

Adrian

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