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Subject: Re: [PATCH] iommu/arm-smmu-v3: fix resource_size check
To:     Masahiro Yamada <yamada.masahiro@socionext.com>,
        Will Deacon <will@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        Joerg Roedel <joro@8bytes.org>,
        iommu@lists.linux-foundation.org
Cc:     linux-kernel@vger.kernel.org
References: <20191226095056.30256-1-yamada.masahiro@socionext.com>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <2cd8ed11-56df-b46b-aa21-5ecc0e2e3082@arm.com>
Date:   Thu, 9 Jan 2020 13:23:14 +0000
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On 26/12/2019 9:50 am, Masahiro Yamada wrote:
> This is an off-by-one mistake.
> 
> resource_size() returns res->end - res->start + 1.

Heh, despite the optimism of "Avoid one-off errors by introducing a 
resource_size() function", life finds a way...

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
> 
>   drivers/iommu/arm-smmu-v3.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index d9e0d9c19b4f..b463599559d2 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -3599,7 +3599,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
>   
>   	/* Base address */
>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (resource_size(res) + 1 < arm_smmu_resource_size(smmu)) {
> +	if (resource_size(res) < arm_smmu_resource_size(smmu)) {
>   		dev_err(dev, "MMIO region too small (%pr)\n", res);
>   		return -EINVAL;
>   	}
>