Re: [PATCH 34/36] tty: serial: pmac_zilog: Make disposable variable __always_unused

Christophe Leroy
2020-11-05T07:05:15Z

Le 04/11/2020 à 20:35, Lee Jones a écrit :
> Fixes the following W=1 kernel build warning(s):
>
> drivers/tty/serial/pmac_zilog.h:365:58: warning: variable ‘garbage’ set but not used [-Wunused-but-set-variable]

Explain how you are fixing this warning.

Setting __always_unused is usually not the good solution for fixing this warning, but here I guess
this is likely the good solution. But it should be explained why.

Christophe

>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Jiri Slaby <jirislaby@kernel.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: linux-serial@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
> drivers/tty/serial/pmac_zilog.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/pmac_zilog.h b/drivers/tty/serial/pmac_zilog.h
> index bb874e76810e0..968aec7c1cf82 100644
> --- a/drivers/tty/serial/pmac_zilog.h
> +++ b/drivers/tty/serial/pmac_zilog.h
> @@ -362,7 +362,7 @@ static inline void zssync(struct uart_pmac_port *port)
>
> /* Misc macros */
> #define ZS_CLEARERR(port) (write_zsreg(port, 0, ERR_RES))
> -#define ZS_CLEARFIFO(port) do { volatile unsigned char garbage; \
> +#define ZS_CLEARFIFO(port) do { volatile unsigned char __always_unused garbage; \
> garbage = read_zsdata(port); \
> garbage = read_zsdata(port); \
> garbage = read_zsdata(port); \
>