Re: [PATCH] drivers: staging: comedi: Fixed side effects from macro definition.

[Ian Abbott]

On 17/02/2021 14:20, chakravarthikulkarni wrote:
> Warning found by checkpatch.pl script.
>
> Signed-off-by: chakravarthikulkarni <chakravarthikulkarni2021@xxxxxxxxx>
> ---
>   drivers/staging/comedi/comedi.h | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h
> index b5d00a006dbb..b2af6a88d389 100644
> --- a/drivers/staging/comedi/comedi.h
> +++ b/drivers/staging/comedi/comedi.h
> @@ -1103,9 +1103,12 @@ enum ni_common_signal_names {
>   
>   /* *** END GLOBALLY-NAMED NI TERMINALS/SIGNALS *** */
>   
> -#define NI_USUAL_PFI_SELECT(x)	(((x) < 10) ? (0x1 + (x)) : (0xb + (x)))
> -#define NI_USUAL_RTSI_SELECT(x)	(((x) < 7) ? (0xb + (x)) : 0x1b)
> -
> +#define NI_USUAL_PFI_SELECT(x) \
> +	({ typeof(x) _x = x; \
> +	 (((_x) < 10) ? (0x1 + (_x)) : (0xb + (_x))); })
> +#define NI_USUAL_RTSI_SELECT(x)	\
> +	({ typeof(x) _x = x; \
> +	 (((_x) < 7) ? (0xb + (_x)) : 0x1b); })
>   /*
>    * mode bits for NI general-purpose counters, set with
>    * INSN_CONFIG_SET_COUNTER_MODE

I'd rather not do that because this is intended to be a userspace 
header.  This change adds GCC extensions and prohibits the use of the 
macros in constant expressions.

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