path: root/drivers/vfio
diff options
authorAlex Williamson <alex.williamson@redhat.com>2013-02-14 14:02:13 -0700
committerAlex Williamson <alex.williamson@redhat.com>2013-02-14 14:02:13 -0700
commite014e9444aedc365742d533e1443b22470cc67b9 (patch)
tree5647eca5f1a28297b023fd1a7b9b1c37030de9a6 /drivers/vfio
parent906ee99dd2a5c819c1171ce5eaf6c080c027e58c (diff)
vfio: Protect vfio_dev_present against device_del
vfio_dev_present is meant to give us a wait_event callback so that we can block removing a device from vfio until it becomes unused. The root of this check depends on being able to get the iommu group from the device. Unfortunately if the BUS_NOTIFY_DEL_DEVICE notifier has fired then the device-group reference is no longer searchable and we fail the lookup. We don't need to go to such extents for this though. We have a reference to the device, from which we can acquire a reference to the group. We can then use the group reference to search for the device and properly block removal. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio')
1 files changed, 12 insertions, 21 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 12c264d3b05..8e6dcecbc40 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -642,33 +642,16 @@ int vfio_add_group_dev(struct device *dev,
-/* Test whether a struct device is present in our tracking */
-static bool vfio_dev_present(struct device *dev)
+/* Given a referenced group, check if it contains the device */
+static bool vfio_dev_present(struct vfio_group *group, struct device *dev)
- struct iommu_group *iommu_group;
- struct vfio_group *group;
struct vfio_device *device;
- iommu_group = iommu_group_get(dev);
- if (!iommu_group)
- return false;
- group = vfio_group_get_from_iommu(iommu_group);
- if (!group) {
- iommu_group_put(iommu_group);
- return false;
- }
device = vfio_group_get_device(group, dev);
- if (!device) {
- vfio_group_put(group);
- iommu_group_put(iommu_group);
+ if (!device)
return false;
- }
- vfio_group_put(group);
- iommu_group_put(iommu_group);
return true;
@@ -682,10 +665,18 @@ void *vfio_del_group_dev(struct device *dev)
struct iommu_group *iommu_group = group->iommu_group;
void *device_data = device->device_data;
+ /*
+ * The group exists so long as we have a device reference. Get
+ * a group reference and use it to scan for the device going away.
+ */
+ vfio_group_get(group);
/* TODO send a signal to encourage this to be released */
- wait_event(vfio.release_q, !vfio_dev_present(dev));
+ wait_event(vfio.release_q, !vfio_dev_present(group, dev));
+ vfio_group_put(group);