linux-kernel - Re: [PATCH v3 5/8] perf tool: Add support for HiSilicon PCIe Tune and Trace device driver

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Message-ID: <20220207115531.0000392f@Huawei.com>
Date:   Mon, 7 Feb 2022 11:55:31 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Yicong Yang <yangyicong@...ilicon.com>
CC:     <gregkh@...uxfoundation.org>, <helgaas@...nel.org>,
        <alexander.shishkin@...ux.intel.com>, <lorenzo.pieralisi@....com>,
        <will@...nel.org>, <mark.rutland@....com>,
        <mathieu.poirier@...aro.org>, <suzuki.poulose@....com>,
        <mike.leach@...aro.org>, <leo.yan@...aro.org>,
        <daniel.thompson@...aro.org>, <joro@...tes.org>,
        <john.garry@...wei.com>, <shameerali.kolothum.thodi@...wei.com>,
        <robin.murphy@....com>, <peterz@...radead.org>, <mingo@...hat.com>,
        <acme@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <coresight@...ts.linaro.org>, <linux-pci@...r.kernel.org>,
        <linux-perf-users@...r.kernel.org>,
        <iommu@...ts.linux-foundation.org>, <prime.zeng@...wei.com>,
        <liuqi115@...wei.com>, <zhangshaokun@...ilicon.com>,
        <linuxarm@...wei.com>, <song.bao.hua@...ilicon.com>
Subject: Re: [PATCH v3 5/8] perf tool: Add support for HiSilicon PCIe Tune
 and Trace device driver

On Mon, 24 Jan 2022 21:11:15 +0800
Yicong Yang <yangyicong@...ilicon.com> wrote:

> From: Qi Liu <liuqi115@...wei.com>
> 
> 'perf record' and 'perf report --dump-raw-trace' supported in this
> patch.
> 
> Example usage:
> 
> Output will contain raw PTT data and its textual representation, such
> as:
> 
> 0 0 0x5810 [0x30]: PERF_RECORD_AUXTRACE size: 0x400000  offset: 0
> ref: 0xa5d50c725  idx: 0  tid: -1  cpu: 0
> .
> . ... HISI PTT data: size 4194304 bytes
> .  00000000: 00 00 00 00                                 Prefix
> .  00000004: 08 20 00 60                                 Header DW0
> .  00000008: ff 02 00 01                                 Header DW1
> .  0000000c: 20 08 00 00                                 Header DW2
> .  00000010: 10 e7 44 ab                                 Header DW3
> .  00000014: 2a a8 1e 01                                 Time
> .  00000020: 00 00 00 00                                 Prefix
> .  00000024: 01 00 00 60                                 Header DW0
> .  00000028: 0f 1e 00 01                                 Header DW1
> .  0000002c: 04 00 00 00                                 Header DW2
> .  00000030: 40 00 81 02                                 Header DW3
> .  00000034: ee 02 00 00                                 Time
> ....
> 
> Signed-off-by: Qi Liu <liuqi115@...wei.com>
> Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>

Hi. This is unfortunately out of my areas of expertise, so I just
took a quick glance and noticed one generic c thing that could be
tidied up.

> diff --git a/tools/perf/util/hisi_ptt.c b/tools/perf/util/hisi_ptt.c
> new file mode 100644
> index 000000000000..75fa89f3fae3
> --- /dev/null
> +++ b/tools/perf/util/hisi_ptt.c

...

> +
> +static void hisi_ptt_free_queue(void *priv)
> +{
> +	struct hisi_ptt_queue *pttq = priv;
> +
> +	if (!pttq)
> +		return;
> +
> +	free(pttq);

free() is safe against a null ptr, so you don't need the 
if (!pttq) return;

See free(3) man page.

> +}
> +
> +static void hisi_ptt_free_events(struct perf_session *session)
> +{
> +	struct hisi_ptt *ptt = container_of(session->auxtrace, struct hisi_ptt,
> +					    auxtrace);
> +	struct auxtrace_queues *queues = &ptt->queues;
> +	unsigned int i;
> +
> +	for (i = 0; i < queues->nr_queues; i++) {
> +		hisi_ptt_free_queue(queues->queue_array[i].priv);
> +		queues->queue_array[i].priv = NULL;
> +	}
> +	auxtrace_queues__free(queues);
> +}
> +