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SubjectRe: [PATCH v2] IOMMU: enhance dmar to support device hotplug
On Thu, Nov 21, 2013 at 04:21:56PM +0800, Yijing Wang wrote:
> @@ -3641,21 +3681,42 @@ static int device_notifier(struct notifier_block *nb,
> struct device *dev = data;
> struct pci_dev *pdev = to_pci_dev(dev);
> struct dmar_domain *domain;
> + struct dmar_device *dmar_dev;
> + struct dmar_drhd_unit *drhd;
>
> - if (iommu_no_mapping(dev))
> - return 0;
> -
> - domain = find_domain(pdev);
> - if (!domain)
> - return 0;
> + switch (action) {
> + case BUS_NOTIFY_ADD_DEVICE:
> + for_each_drhd_unit(drhd)
> + list_for_each_entry(dmar_dev, &drhd->devices, list)
> + if (dmar_dev->segment == pci_domain_nr(pdev->bus)
> + && dmar_dev->bus == pdev->bus->number
> + && dmar_dev->devfn == pdev->devfn)
> + dmar_dev->pdev = pci_dev_get(pdev);
> + break;
> + case BUS_NOTIFY_DEL_DEVICE:
> + for_each_drhd_unit(drhd)
> + list_for_each_entry(dmar_dev, &drhd->devices, list)
> + if (dmar_dev->pdev == pdev) {
> + pci_dev_put(pdev);
> + dmar_dev->pdev = NULL;
> + }

How is that synchronized with other users of this dmar_dev structure.
Could it happen that you drop the device reference while other parts of
the driver still use it?


Joerg




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