linux-kernel - Re: [PATCH 2/2] coresight: Abort probe for missing CPU phandle

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Date:   Thu, 20 Jun 2019 11:43:08 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Cc:     Suzuki K Poulose <suzuki.poulose@....com>,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/2] coresight: Abort probe for missing CPU phandle

On Thu, Jun 20, 2019 at 07:15:47PM +0530, Sai Prakash Ranjan wrote:
> Currently the coresight etm and cpu-debug drivers
> assume the affinity to CPU0 returned by coresight
> platform and continue the probe in case of missing
> CPU phandle. This is not true and leads to crash
> in some cases, so abort the probe in case of missing
> CPU phandle.
> 
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
> ---
>  drivers/hwtracing/coresight/coresight-cpu-debug.c | 3 +++
>  drivers/hwtracing/coresight/coresight-etm3x.c     | 3 +++
>  drivers/hwtracing/coresight/coresight-etm4x.c     | 3 +++
>  3 files changed, 9 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> index 07a1367c733f..43f32fa71ff9 100644
> --- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
> +++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> @@ -579,6 +579,9 @@ static int debug_probe(struct amba_device *adev, const struct amba_id *id)
>  		return -ENOMEM;
>  
>  	drvdata->cpu = coresight_get_cpu(dev);
> +	if (drvdata->cpu == -ENODEV)
> +		return -ENODEV;

As Suzuki pointed out, simply return the error message conveyed by
coresight_get_cpu().

Also please merge both patches together to avoid bisect nightmare.

Thank you for the contribution,
Mathieu

> +
>  	if (per_cpu(debug_drvdata, drvdata->cpu)) {
>  		dev_err(dev, "CPU%d drvdata has already been initialized\n",
>  			drvdata->cpu);
> diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
> index 225c2982e4fe..882e2751746c 100644
> --- a/drivers/hwtracing/coresight/coresight-etm3x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm3x.c
> @@ -816,6 +816,9 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
>  	}
>  
>  	drvdata->cpu = coresight_get_cpu(dev);
> +	if (drvdata->cpu == -ENODEV)
> +		return -ENODEV;
> +
>  	desc.name  = devm_kasprintf(dev, GFP_KERNEL, "etm%d", drvdata->cpu);
>  	if (!desc.name)
>  		return -ENOMEM;
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> index 7fe266194ab5..97d71dbbeb19 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> @@ -1101,6 +1101,9 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
>  	spin_lock_init(&drvdata->spinlock);
>  
>  	drvdata->cpu = coresight_get_cpu(dev);
> +	if (drvdata->cpu == -ENODEV)
> +		return -ENODEV;
> +
>  	desc.name = devm_kasprintf(dev, GFP_KERNEL, "etm%d", drvdata->cpu);
>  	if (!desc.name)
>  		return -ENOMEM;
> -- 
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>