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

From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
	Leo Yan <leo.yan@linaro.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Andy Gross <andy.gross@linaro.org>,
	David Brown <david.brown@linaro.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Rajendra Nayak <rnayak@codeaurora.org>,
	Vivek Gautam <vivek.gautam@codeaurora.org>,
	Sibi Sankar <sibis@codeaurora.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH 2/2] coresight: Abort probe for missing CPU phandle
Date: Thu, 20 Jun 2019 11:43:08 -0600	[thread overview]
Message-ID: <20190620174308.GB5581@xps15> (raw)
In-Reply-To: <d93e28fc80227f9a385130a766a24f8f39a1dcf0.1561037262.git.saiprakash.ranjan@codeaurora.org>

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@codeaurora.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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> 