linux-kernel - Re: [PATCH v2 2/2] perf tools: ARM SPE code cleanup

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Date:   Mon, 27 Jul 2020 14:34:36 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Wei Li <liwei391@...wei.com>
Cc:     leo.yan@...aro.org, Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Kim Phillips <kim.phillips@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, guohanjun@...wei.com
Subject: Re: [PATCH v2 2/2] perf tools: ARM SPE code cleanup

On Fri, Jul 24, 2020 at 03:11:11PM +0800, Wei Li wrote:
> - Firstly, the function auxtrace_record__init() will be invoked only
>   once, the variable "arm_spe_pmus" will not be used afterwards, thus
>   we don't need to check "arm_spe_pmus" is NULL or not;
> - Another reason is, even though SPE is micro-architecture dependent,
>   but so far it only supports "statistical-profiling-extension-v1" and
>   we have no chance to use multiple SPE's PMU events in Perf command.

I find the above changelog somewhat out of touch with the patch itself.  The
only thing that is happening here is the removal of a useless check and a fix
for a memory leak.

Once again whether Arnaldo wants to make the changes by hand or not you may have
to resubmit.

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

> 
> So remove the useless check code to make it clear.
> 
> Signed-off-by: Wei Li <liwei391@...wei.com>
> ---
>  tools/perf/arch/arm/util/auxtrace.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/arch/arm/util/auxtrace.c b/tools/perf/arch/arm/util/auxtrace.c
> index 28a5d0c18b1d..b187bddbd01a 100644
> --- a/tools/perf/arch/arm/util/auxtrace.c
> +++ b/tools/perf/arch/arm/util/auxtrace.c
> @@ -57,17 +57,15 @@ struct auxtrace_record
>  	struct evsel *evsel;
>  	bool found_etm = false;
>  	struct perf_pmu *found_spe = NULL;
> -	static struct perf_pmu **arm_spe_pmus = NULL;
> -	static int nr_spes = 0;
> +	struct perf_pmu **arm_spe_pmus = NULL;
> +	int nr_spes = 0;
>  	int i = 0;
>  
>  	if (!evlist)
>  		return NULL;
>  
>  	cs_etm_pmu = perf_pmu__find(CORESIGHT_ETM_PMU_NAME);
> -
> -	if (!arm_spe_pmus)
> -		arm_spe_pmus = find_all_arm_spe_pmus(&nr_spes, err);
> +	arm_spe_pmus = find_all_arm_spe_pmus(&nr_spes, err);
>  
>  	evlist__for_each_entry(evlist, evsel) {
>  		if (cs_etm_pmu &&
> @@ -84,6 +82,7 @@ struct auxtrace_record
>  			}
>  		}
>  	}
> +	free(arm_spe_pmus);
>  
>  	if (found_etm && found_spe) {
>  		pr_err("Concurrent ARM Coresight ETM and SPE operation not currently supported\n");
> -- 
> 2.17.1
>