linux-kernel - Re: [PATCH V8 9/9] virtio: Intel IFC VF driver for VDPA

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Message-ID: <ed04692d-236c-2eee-4429-6ef4d5d165fe@redhat.com>
Date:   Thu, 26 Mar 2020 13:50:53 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Jason Gunthorpe <jgg@...lanox.com>
Cc:     mst@...hat.com, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        maxime.coquelin@...hat.com, cunming.liang@...el.com,
        zhihong.wang@...el.com, rob.miller@...adcom.com,
        xiao.w.wang@...el.com, lingshan.zhu@...el.com, eperezma@...hat.com,
        lulu@...hat.com, parav@...lanox.com, kevin.tian@...el.com,
        stefanha@...hat.com, rdunlap@...radead.org, hch@...radead.org,
        aadam@...hat.com, jiri@...lanox.com, shahafs@...lanox.com,
        hanand@...inx.com, mhabets@...arflare.com, gdawar@...inx.com,
        saugatm@...inx.com, vmireyno@...vell.com,
        Bie Tiwei <tiwei.bie@...el.com>
Subject: Re: [PATCH V8 9/9] virtio: Intel IFC VF driver for VDPA


On 2020/3/25 下午8:34, Jason Gunthorpe wrote:
> On Wed, Mar 25, 2020 at 04:27:11PM +0800, Jason Wang wrote:
>> +static int ifcvf_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct ifcvf_adapter *adapter;
>> +	struct ifcvf_hw *vf;
>> +	int ret, i;
>> +
>> +	ret = pci_enable_device(pdev);
>> +	if (ret) {
>> +		IFCVF_ERR(&pdev->dev, "Failed to enable device\n");
>> +		goto err_enable;
>> +	}
>> +
>> +	ret = pci_request_regions(pdev, IFCVF_DRIVER_NAME);
>> +	if (ret) {
>> +		IFCVF_ERR(&pdev->dev, "Failed to request MMIO region\n");
>> +		goto err_regions;
>> +	}
>> +
>> +	ret = pci_alloc_irq_vectors(pdev, IFCVF_MAX_INTR,
>> +				    IFCVF_MAX_INTR, PCI_IRQ_MSIX);
>> +	if (ret < 0) {
>> +		IFCVF_ERR(&pdev->dev, "Failed to alloc irq vectors\n");
>> +		goto err_vectors;
>> +	}
>> +
>> +	adapter = vdpa_alloc_device(ifcvf_adapter, vdpa, dev, &ifc_vdpa_ops);
>> +	if (adapter == NULL) {
>> +		IFCVF_ERR(&pdev->dev, "Failed to allocate vDPA structure");
>> +		ret = -ENOMEM;
>> +		goto err_alloc;
>> +	}
>> +
>> +	adapter->dev = dev;
>> +	pci_set_master(pdev);
>> +	pci_set_drvdata(pdev, adapter);
>> +
>> +	ret = ifcvf_request_irq(adapter);
>> +	if (ret) {
>> +		IFCVF_ERR(&pdev->dev, "Failed to request MSI-X irq\n");
>> +		goto err_msix;
>> +	}
>> +
>> +	vf = &adapter->vf;
>> +	for (i = 0; i < IFCVF_PCI_MAX_RESOURCE; i++) {
>> +		vf->mem_resource[i].phys_addr = pci_resource_start(pdev, i);
>> +		vf->mem_resource[i].len = pci_resource_len(pdev, i);
>> +		if (!vf->mem_resource[i].len)
>> +			continue;
>> +
>> +		vf->mem_resource[i].addr = pci_iomap_range(pdev, i, 0,
>> +				vf->mem_resource[i].len);
>> +		if (!vf->mem_resource[i].addr) {
>> +			IFCVF_ERR(&pdev->dev,
>> +				  "Failed to map IO resource %d\n", i);
>> +			ret = -EINVAL;
>> +			goto err_msix;
>> +		}
>> +	}
>> +
>> +	if (ifcvf_init_hw(vf, pdev) < 0) {
>> +		ret = -EINVAL;
>> +		goto err_msix;
>> +	}
>> +
>> +	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
>> +	if (ret)
>> +		ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
>> +
>> +	if (ret) {
>> +		IFCVF_ERR(adapter->dev, "No usable DMA confiugration\n");
>> +		ret = -EINVAL;
>> +		goto err_msix;
>> +	}
>> +
>> +	adapter->vdpa.dma_dev = dev;
>> +	ret = vdpa_register_device(&adapter->vdpa);
>> +	if (ret) {
>> +		IFCVF_ERR(adapter->dev, "Failed to register ifcvf to vdpa bus");
>> +		goto err_msix;
>> +	}
>> +
>> +	return 0;
>> +
>> +err_msix:
>> +	put_device(&adapter->vdpa.dev);
>> +	return ret;
>> +err_alloc:
>> +	pci_free_irq_vectors(pdev);
>> +err_vectors:
>> +	pci_release_regions(pdev);
>> +err_regions:
>> +	pci_disable_device(pdev);
>> +err_enable:
>> +	return ret;
>> +}
> I personally don't like seeing goto unwinds with multiple returns, and
> here I think it is actually a tiny bug.
>
> All touches to the PCI device must stop before the driver core
> remove() returns - so these pci function cannot be in the kref put
> release function anyhow.


I'm not sure I get here. IFCVF held refcnt of its PCI parent, so it 
looks to me it's safe to free PCI resources in vDPA free callback?


>
> Suggest to use the devm versions of the above instead, and then you
> can reorder things so the allocation is done first.
>
> Jason


Using devm looks nice, but if it's possible I prefer to tweak on top.

Thanks


>