Re: [PATCH] perf cs-etm: use swap() to make code cleaner

[Leo Yan]

Hi Yihao,

On Thu, Nov 11, 2021 at 06:33:44PM -0800, Yihao Han wrote:
> Use the macro 'swap()' defined in 'include/linux/minmax.h' to avoid
> opencoding it.

The header 'include/linux/minmax.h' is used for kernel but it's not
provided for user space program?

> Signed-off-by: Yihao Han <hanyihao@xxxxxxxx>
> ---
>  tools/perf/util/cs-etm.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index f323adb1af85..aaa3ec725002 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -408,17 +408,13 @@ struct cs_etm_packet_queue
>  static void cs_etm__packet_swap(struct cs_etm_auxtrace *etm,
>  				struct cs_etm_traceid_queue *tidq)
>  {
> -	struct cs_etm_packet *tmp;
> -
>  	if (etm->sample_branches || etm->synth_opts.last_branch ||
>  	    etm->sample_instructions) {
>  		/*
>  		 * Swap PACKET with PREV_PACKET: PACKET becomes PREV_PACKET for
>  		 * the next incoming packet.
>  		 */
> -		tmp = tidq->packet;
> -		tidq->packet = tidq->prev_packet;
> -		tidq->prev_packet = tmp;
> +		swap(tidq->packet, tidq->prev_packet);

NAK - This patch will introduce compilation error:

util/cs-etm.c: In function ‘cs_etm__packet_swap’:
util/cs-etm.c:417:3: error: implicit declaration of function ‘swap’; did you mean ‘swab’? [-Werror=implicit-function-declaration]
   swap(tidq->packet, tidq->prev_packet);
   ^~~~
   swab

Thanks,
Leo

>  	}
>  }
>  
> -- 
> 2.17.1
>