Re: [PATCH v8 4/8] perf arm: Refactor event list iteration in auxtrace_record__init()

From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Yicong Yang <yangyicong@hisilicon.com>
Cc: <gregkh@linuxfoundation.org>,
	<alexander.shishkin@linux.intel.com>, <leo.yan@linaro.org>,
	<james.clark@arm.com>, <will@kernel.org>, <robin.murphy@arm.com>,
	<acme@kernel.org>, <john.garry@huawei.com>, <helgaas@kernel.org>,
	<lorenzo.pieralisi@arm.com>, <mathieu.poirier@linaro.org>,
	<suzuki.poulose@arm.com>, <mark.rutland@arm.com>,
	<joro@8bytes.org>, <shameerali.kolothum.thodi@huawei.com>,
	<peterz@infradead.org>, <mingo@redhat.com>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-pci@vger.kernel.org>, <linux-perf-users@vger.kernel.org>,
	<iommu@lists.linux-foundation.org>, <prime.zeng@huawei.com>,
	<liuqi115@huawei.com>, <zhangshaokun@hisilicon.com>,
	<linuxarm@huawei.com>
Subject: Re: [PATCH v8 4/8] perf arm: Refactor event list iteration in auxtrace_record__init()
Date: Mon, 16 May 2022 15:17:22 +0100	[thread overview]
Message-ID: <20220516151722.0000693a@Huawei.com> (raw)
In-Reply-To: <20220516125223.32012-5-yangyicong@hisilicon.com>

On Mon, 16 May 2022 20:52:19 +0800
Yicong Yang <yangyicong@hisilicon.com> wrote:

> From: Qi Liu <liuqi115@huawei.com>
> 
> Use find_pmu_for_event() to simplify logic in auxtrace_record__init().
Possibly reword as 

"Add find_pmu_for_event() and use to simplify logic in
auxtrace_record_init(). find_pmu_for_event() will be
reused in subsequent patches."

> 
> Signed-off-by: Qi Liu <liuqi115@huawei.com>
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
FWIW as this isn't an area I know much about. It seems
like a good cleanup and functionally equivalent.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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);
>  	}
> +
>  	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;
>  	}