linux-kernel - Re: [PATCH v5 8/9] vfio/pci: Enable peer-to-peer DMA transactions by default

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Message-ID: <aPBwEVJSzezdii1V@Asurada-Nvidia>
Date: Wed, 15 Oct 2025 21:09:53 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: Leon Romanovsky <leon@...nel.org>
CC: Alex Williamson <alex.williamson@...hat.com>, Leon Romanovsky
	<leonro@...dia.com>, Jason Gunthorpe <jgg@...dia.com>, Andrew Morton
	<akpm@...ux-foundation.org>, Bjorn Helgaas <bhelgaas@...gle.com>, Christian
 König <christian.koenig@....com>,
	<dri-devel@...ts.freedesktop.org>, <iommu@...ts.linux.dev>, Jens Axboe
	<axboe@...nel.dk>, Joerg Roedel <joro@...tes.org>, <kvm@...r.kernel.org>,
	<linaro-mm-sig@...ts.linaro.org>, <linux-block@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
	<linux-mm@...ck.org>, <linux-pci@...r.kernel.org>, Logan Gunthorpe
	<logang@...tatee.com>, Marek Szyprowski <m.szyprowski@...sung.com>, "Robin
 Murphy" <robin.murphy@....com>, Sumit Semwal <sumit.semwal@...aro.org>,
	"Vivek Kasireddy" <vivek.kasireddy@...el.com>, Will Deacon <will@...nel.org>
Subject: Re: [PATCH v5 8/9] vfio/pci: Enable peer-to-peer DMA transactions by
 default

Hi Leon,

On Mon, Oct 13, 2025 at 06:26:10PM +0300, Leon Romanovsky wrote:
> @@ -2090,6 +2092,9 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev)
>  	INIT_LIST_HEAD(&vdev->dummy_resources_list);
>  	INIT_LIST_HEAD(&vdev->ioeventfds_list);
>  	INIT_LIST_HEAD(&vdev->sriov_pfs_item);
> +	ret = pcim_p2pdma_init(vdev->pdev);
> +	if (ret != -EOPNOTSUPP)
> +		return ret;
>  	init_rwsem(&vdev->memory_lock);
>  	xa_init(&vdev->ctx);

I think this should be:
	if (ret && ret != -EOPNOTSUPP)
		return ret;

Otherwise, init_rwsem() and xa_init() would be missed if ret==0.

Thanks
Nicolin