Re: [dpdk-dev] [PATCH] eal: avoid side effects in RTE_ALIGN_MUL_NEAR(v, mul) for v and mul

[Ranjit Menon <ranjit.menon@intel.com>]

On 3/11/2021 1:08 PM, Tyler Retzlaff wrote:
> Avoid expanding v and mul parameters multiple times in the macro. based
> on usage of the macro it seems like side effects were not intended.
>
> For example:
>    ``return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, CYC_PER_10MHZ);''
>
> Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
> ---
>   lib/librte_eal/include/rte_common.h | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_eal/include/rte_common.h b/lib/librte_eal/include/rte_common.h
> index 1b630baf1..640befee2 100644
> --- a/lib/librte_eal/include/rte_common.h
> +++ b/lib/librte_eal/include/rte_common.h
> @@ -345,9 +345,11 @@ static void __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
>    */
>   #define RTE_ALIGN_MUL_NEAR(v, mul)				\
>   	({							\
> -		typeof(v) ceil = RTE_ALIGN_MUL_CEIL(v, mul);	\
> -		typeof(v) floor = RTE_ALIGN_MUL_FLOOR(v, mul);	\
> -		(ceil - (v)) > ((v) - floor) ? floor : ceil;	\
> +		typeof(v) _v = (v);				\
> +		typeof(v) _m = (mul);				\
For consistency sake, can this variable be changed to '_mul'?
> +		typeof(v) ceil = RTE_ALIGN_MUL_CEIL(_v, _m);	\
> +		typeof(v) floor = RTE_ALIGN_MUL_FLOOR(_v, _m);	\
> +		(ceil - (_v)) > ((_v) - floor) ? floor : ceil;	\
>   	})
>   
>   /**


ranjit m.