linux-kernel - Re: [PATCH v2] hwtracing: hisi_ptt: Move type check to the beginning of hisi_ptt_pmu_event

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Message-ID: <fd4037ad-59df-d3e2-0fe9-bde0182ce79f@huawei.com>
Date: Mon, 8 Jan 2024 20:29:09 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: Yang Jihong <yangjihong1@...wei.com>
CC: <suzuki.poulose@....com>, <wangkefeng.wang@...wei.com>,
	<yangyicong@...ilicon.com>, <alexander.shishkin@...ux.intel.com>,
	<jonathan.cameron@...wei.com>, <john.garry@...wei.com>,
	<mathieu.poirier@...aro.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] hwtracing: hisi_ptt: Move type check to the beginning
 of hisi_ptt_pmu_event_init()

Hi Jihong,

On 2024/1/8 20:19, Yang Jihong wrote:
> When perf_init_event() calls perf_try_init_event() to init pmu driver,
> searches for the next pmu driver only when the return value is -ENOENT.
> Therefore, hisi_ptt_pmu_event_init() needs to check the type at the
> beginning of the function.
> Otherwise, in the case of perf-task mode, perf_try_init_event() returns
> -EOPNOTSUPP and skips subsequent pmu drivers, causes perf_init_event() to
> fail.
> 
> Fixes: ff0de066b463 ("hwtracing: hisi_ptt: Add trace function support for HiSilicon PCIe Tune and Trace device")
> Signed-off-by: Yang Jihong <yangjihong1@...wei.com>

Thanks for fixing this:

Reviewed-by: Yicong Yang <yangyicong@...ilicon.com>

> ---
> 
> Changes since v1:
>  - Add fixes tag.
> 
>  drivers/hwtracing/ptt/hisi_ptt.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
> index a991ecb7515a..24a1f7797aeb 100644
> --- a/drivers/hwtracing/ptt/hisi_ptt.c
> +++ b/drivers/hwtracing/ptt/hisi_ptt.c
> @@ -995,6 +995,9 @@ static int hisi_ptt_pmu_event_init(struct perf_event *event)
>  	int ret;
>  	u32 val;
>  
> +	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
> +		return -ENOENT;
> +
>  	if (event->cpu < 0) {
>  		dev_dbg(event->pmu->dev, "Per-task mode not supported\n");
>  		return -EOPNOTSUPP;
> @@ -1003,9 +1006,6 @@ static int hisi_ptt_pmu_event_init(struct perf_event *event)
>  	if (event->attach_state & PERF_ATTACH_TASK)
>  		return -EOPNOTSUPP;
>  
> -	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
> -		return -ENOENT;
> -
>  	ret = hisi_ptt_trace_valid_filter(hisi_ptt, event->attr.config);
>  	if (ret < 0)
>  		return ret;
>