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vfio: Tie IOMMU group reference to vfio group

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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: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2015-02-06 15:05:06 -07:00
parent 60720a0fc6
commit 4a68810dbb
1 changed files with 11 additions and 8 deletions
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19
drivers/vfio/vfio.c
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@ -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);