linux-kernel - Re: [PATCH v2] iommu/qcom: Fix local

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Date:   Sun, 19 Apr 2020 14:32:20 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Tang Bin <tangbin@...s.chinamobile.com>,
        iommu@...ts.linux-foundation.org, linux-arm-msm@...r.kernel.org,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Jörg Rödel <joro@...tes.org>,
        Rob Clark <robdclark@...il.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] iommu/qcom: Fix local_base status check

> The function qcom_iommu_device_probe() does not perform sufficient
> error checking after executing devm_ioremap_resource(), which can
> result in crashes if a critical error path is encountered.

Your update suggestion will be rechecked once more.

* Can it be that the patch would need a higher version number
  according to previous review comments?

* Would you like to adjust the patch subject?

…
> +++ b/drivers/iommu/qcom_iommu.c
> @@ -813,8 +813,11 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
>  	qcom_iommu->dev = dev;
>
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (res)

I find the deletion of this check appropriate.

> +	if (res) {
>  		qcom_iommu->local_base = devm_ioremap_resource(dev, res);

But I do not see a need to preserve such a check because this function
performs input parameter validation.
https://elixir.bootlin.com/linux/v5.7-rc1/source/lib/devres.c#L116
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/devres.c?id=50cc09c18985eacbbd666acfd7be2391394733f5#n116

Please take another look at a corresponding usage example.

Regards,
Markus