linux-kernel - Re: [PATCH v1 2/3] iommu/vt-d: Change dmar_ats

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Message-ID: <b36f7eeb-c6ed-4f80-969f-a33a619b954b@intel.com>
Date: Fri, 9 May 2025 17:27:23 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: Wei Wang <wei.w.wang@...el.com>, <dwmw2@...radead.org>,
	<baolu.lu@...ux.intel.com>, <kevin.tian@...el.com>, <jroedel@...e.de>,
	<linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>
Subject: Re: [PATCH v1 2/3] iommu/vt-d: Change dmar_ats_supported() to return
 boolean

On 2025/5/9 22:00, Wei Wang wrote:
> According to "Function return values and names" in coding-style.rst, the
> dmar_ats_supported() function should return a boolean instead of an
> integer. Also, rename "ret" to "supported" to be more straightforward.
>

seems just a recommendation since this is just internal helper. The
function was indeed not well written anyhow. :) not sure if Baolu wants
take it or not. Taking it may make history tracking harder. Patch itself
looks good to me.

Reviewed-by: Yi Liu <yi.l.liu@...el.com>

> Signed-off-by: Wei Wang <wei.w.wang@...el.com>
> ---
>   drivers/iommu/intel/iommu.c | 13 +++++++------
>   1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index d8aa71305509..2778bfe14f36 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -2760,10 +2760,11 @@ static struct dmar_satc_unit *dmar_find_matched_satc_unit(struct pci_dev *dev)
>   	return satcu;
>   }
>   
> -static int dmar_ats_supported(struct pci_dev *dev, struct intel_iommu *iommu)
> +static bool dmar_ats_supported(struct pci_dev *dev, struct intel_iommu *iommu)
>   {
> -	int i, ret = 1;
> +	int i;
>   	struct pci_bus *bus;
> +	bool supported = true;
>   	struct pci_dev *bridge = NULL;
>   	struct device *tmp;
>   	struct acpi_dmar_atsr *atsr;

This list should have been in reverse Christmas tree order per the length. :)

> @@ -2786,11 +2787,11 @@ static int dmar_ats_supported(struct pci_dev *dev, struct intel_iommu *iommu)
>   		bridge = bus->self;
>   		/* If it's an integrated device, allow ATS */
>   		if (!bridge)
> -			return 1;
> +			return true;
>   		/* Connected via non-PCIe: no ATS */
>   		if (!pci_is_pcie(bridge) ||
>   		    pci_pcie_type(bridge) == PCI_EXP_TYPE_PCI_BRIDGE)
> -			return 0;
> +			return false;
>   		/* If we found the root port, look it up in the ATSR */
>   		if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
>   			break;
> @@ -2809,11 +2810,11 @@ static int dmar_ats_supported(struct pci_dev *dev, struct intel_iommu *iommu)
>   		if (atsru->include_all)
>   			goto out;
>   	}
> -	ret = 0;
> +	supported = false;
>   out:
>   	rcu_read_unlock();
>   
> -	return ret;
> +	return supported;
>   }
>   
>   int dmar_iommu_notify_scope_dev(struct dmar_pci_notify_info *info)

-- 
Regards,
Yi Liu