linux-kernel - Re: [RESEND PATCH v12 1/3] perf tool: arm: Refactor event list iteration in auxtrace_record_

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Date:   Wed, 14 Sep 2022 14:47:43 +0100
From:   John Garry <john.garry@...wei.com>
To:     Yicong Yang <yangyicong@...wei.com>, <acme@...nel.org>,
        <peterz@...radead.org>, <alexander.shishkin@...ux.intel.com>,
        <leo.yan@...aro.org>, <james.clark@....com>, <will@...nel.org>,
        <mathieu.poirier@...aro.org>, <mark.rutland@....com>,
        <suzuki.poulose@....com>, <jonathan.cameron@...wei.com>,
        <mike.leach@...aro.org>
CC:     <gregkh@...uxfoundation.org>, <helgaas@...nel.org>,
        <lorenzo.pieralisi@....com>,
        <shameerali.kolothum.thodi@...wei.com>, <mingo@...hat.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-pci@...r.kernel.org>, <linux-perf-users@...r.kernel.org>,
        <prime.zeng@...wei.com>, <zhangshaokun@...ilicon.com>,
        <linuxarm@...wei.com>, <yangyicong@...ilicon.com>,
        <liuqi6124@...il.com>
Subject: Re: [RESEND PATCH v12 1/3] perf tool: arm: Refactor event list
 iteration in auxtrace_record__init()

On 14/09/2022 08:59, Yicong Yang wrote:
> From: Qi Liu <liuqi115@...wei.com>
> 
> Add find_pmu_for_event() and use to simplify logic in
> auxtrace_record_init(). find_pmu_for_event() will be
> reused in subsequent patches.
> 
> Reviewed-by: Leo Yan <leo.yan@...aro.org>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Signed-off-by: Qi Liu <liuqi115@...wei.com>
> Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>
> ---
>   tools/perf/arch/arm/util/auxtrace.c | 53 ++++++++++++++++++-----------
>   1 file changed, 34 insertions(+), 19 deletions(-)
> 
> diff --git a/tools/perf/arch/arm/util/auxtrace.c b/tools/perf/arch/arm/util/auxtrace.c
> index 5fc6a2a3dbc5..384c7cfda0fd 100644
> --- a/tools/perf/arch/arm/util/auxtrace.c
> +++ b/tools/perf/arch/arm/util/auxtrace.c
> @@ -50,16 +50,32 @@ static struct perf_pmu **find_all_arm_spe_pmus(int *nr_spes, int *err)
>   	return arm_spe_pmus;
>   }
>   
> +static struct perf_pmu *find_pmu_for_event(struct perf_pmu **pmus,
> +					   int pmu_nr, struct evsel *evsel)
> +{
> +	int i;
> +
> +	if (!pmus)
> +		return NULL;
> +
> +	for (i = 0; i < pmu_nr; i++) {
> +		if (evsel->core.attr.type == pmus[i]->type)
> +			return pmus[i];
> +	}
> +
> +	return NULL;
> +}
> +
>   struct auxtrace_record
>   *auxtrace_record__init(struct evlist *evlist, int *err)
>   {
> -	struct perf_pmu	*cs_etm_pmu;
> +	struct perf_pmu	*cs_etm_pmu = NULL;
> +	struct perf_pmu **arm_spe_pmus = NULL;
>   	struct evsel *evsel;
> -	bool found_etm = false;
> +	struct perf_pmu *found_etm = NULL;
>   	struct perf_pmu *found_spe = NULL;
> -	struct perf_pmu **arm_spe_pmus = NULL;
> +	int auxtrace_event_cnt = 0;
>   	int nr_spes = 0;
> -	int i = 0;
>   
>   	if (!evlist)
>   		return NULL;
> @@ -68,24 +84,23 @@ struct auxtrace_record
>   	arm_spe_pmus = find_all_arm_spe_pmus(&nr_spes, err);
>   
>   	evlist__for_each_entry(evlist, evsel) {
> -		if (cs_etm_pmu &&
> -		    evsel->core.attr.type == cs_etm_pmu->type)
> -			found_etm = true;
> -
> -		if (!nr_spes || found_spe)
> -			continue;
> -
> -		for (i = 0; i < nr_spes; i++) {
> -			if (evsel->core.attr.type == arm_spe_pmus[i]->type) {
> -				found_spe = arm_spe_pmus[i];
> -				break;
> -			}
> -		}
> +		if (cs_etm_pmu && !found_etm) 
> +			found_etm = find_pmu_for_event(&cs_etm_pmu, 1, evsel);
> +
> +		if (arm_spe_pmus && !found_spe)
> +			found_spe = find_pmu_for_event(arm_spe_pmus, nr_spes, evsel);

should you break if found_etm and found_spe are set? Or, indeed, error 
and return directly as we do below? Indeed, I am not sure why you even 
require auxtrace_event_cnt

>   	}
> +
>   	free(arm_spe_pmus);
>   
> -	if (found_etm && found_spe) {
> -		pr_err("Concurrent ARM Coresight ETM and SPE operation not currently supported\n");
> +	if (found_etm)
> +		auxtrace_event_cnt++;
> +
> +	if (found_spe)
> +		auxtrace_event_cnt++;
> +
> +	if (auxtrace_event_cnt > 1) {
> +		pr_err("Concurrent AUX trace operation not currently supported\n");
>   		*err = -EOPNOTSUPP;
>   		return NULL;
>   	}