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Subject: Re: [PATCH v2] hwtracing: hisi_ptt: Move type check to the beginning
 of hisi_ptt_pmu_event_init()
To: Suzuki Poulouse <suzuki.poulose@arm.com>
CC: <wangkefeng.wang@huawei.com>, <yangyicong@huawei.com>,
	<yangyicong@hisilicon.com>, <jonathan.cameron@huawei.com>,
	<alexander.shishkin@linux.intel.com>, <mathieu.poirier@linaro.org>,
	<john.garry@huawei.com>, <linux-kernel@vger.kernel.org>
References: <20240108121906.3514820-1-yangjihong1@huawei.com>
From: Yang Jihong <yangjihong1@huawei.com>
Message-ID: <979bdbe5-f01a-dfa8-6550-0f684d8f3b08@huawei.com>
Date: Mon, 26 Feb 2024 09:06:19 +0800
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Hello,

PING.

Thanks,
Yang

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@huawei.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;
>