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Commit 4a68810d authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio: Tie IOMMU group reference to vfio group 



Move the iommu_group reference from the device to the vfio_group.
This ensures that the iommu_group persists as long as the vfio_group
remains.  This can be important if all of the device from an
iommu_group are removed, but we still have an outstanding vfio_group
reference; we can still walk the empty list of devices.

Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 60720a0f

drivers/vfio/vfio.c

+11 −8
Original line number Diff line number Diff line
@@ -274,6 +274,7 @@ static void vfio_group_release(struct kref *kref) 
{

	struct vfio_group *group = container_of(kref, struct vfio_group, kref);

	struct vfio_unbound_dev *unbound, *tmp;

	struct iommu_group *iommu_group = group->iommu_group;



	WARN_ON(!list_empty(&group->device_list));
@@ -287,6 +288,7 @@ static void vfio_group_release(struct kref *kref) 
	list_del(&group->vfio_next);

	vfio_free_group_minor(group->minor);

	vfio_group_unlock_and_free(group);

	iommu_group_put(iommu_group);

}



static void vfio_group_put(struct vfio_group *group)
@@ -625,6 +627,12 @@ int vfio_add_group_dev(struct device *dev, 
			iommu_group_put(iommu_group);

			return PTR_ERR(group);

		}

	} else {

		/*

		 * A found vfio_group already holds a reference to the

		 * iommu_group.  A created vfio_group keeps the reference.

		 */

		iommu_group_put(iommu_group);

	}



	device = vfio_group_get_device(group, dev);
@@ -633,21 +641,19 @@ int vfio_add_group_dev(struct device *dev, 
		     dev_name(dev), iommu_group_id(iommu_group));

		vfio_device_put(device);

		vfio_group_put(group);

		iommu_group_put(iommu_group);

		return -EBUSY;

	}



	device = vfio_group_create_device(group, dev, ops, device_data);

	if (IS_ERR(device)) {

		vfio_group_put(group);

		iommu_group_put(iommu_group);

		return PTR_ERR(device);

	}



	/*

	 * Added device holds reference to iommu_group and vfio_device

	 * (which in turn holds reference to vfio_group).  Drop extra

	 * group reference used while acquiring device.

	 * Drop all but the vfio_device reference.  The vfio_device holds

	 * a reference to the vfio_group, which holds a reference to the

	 * iommu_group.

	 */

	vfio_group_put(group);
@@ -702,7 +708,6 @@ void *vfio_del_group_dev(struct device *dev) 
{

	struct vfio_device *device = dev_get_drvdata(dev);

	struct vfio_group *group = device->group;

	struct iommu_group *iommu_group = group->iommu_group;

	void *device_data = device->device_data;

	struct vfio_unbound_dev *unbound;
@@ -737,8 +742,6 @@ void *vfio_del_group_dev(struct device *dev) 


	vfio_group_put(group);



	iommu_group_put(iommu_group);



	return device_data;

}

EXPORT_SYMBOL_GPL(vfio_del_group_dev);