2 files changed, 24 insertions, 2 deletions

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 13e0f39d91e0..4cde85501444 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -710,6 +710,7 @@ void *vfio_del_group_dev(struct device *dev)
         struct vfio_group *group = device->group;
         void *device_data = device->device_data;
         struct vfio_unbound_dev *unbound;
+        unsigned int i = 0;
 
         /*
          * The group exists so long as we have a device reference.  Get
@@ -737,8 +738,27 @@ void *vfio_del_group_dev(struct device *dev)
 
         vfio_device_put(device);
 
-        /* TODO send a signal to encourage this to be released */
-        wait_event(vfio.release_q, !vfio_dev_present(group, dev));
+        /*
+         * If the device is still present in the group after the above
+         * 'put', then it is in use and we need to request it from the
+         * bus driver.  The driver may in turn need to request the
+         * device from the user.  We send the request on an arbitrary
+         * interval with counter to allow the driver to take escalating
+         * measures to release the device if it has the ability to do so.
+         */
+        do {
+                device = vfio_group_get_device(group, dev);
+                if (!device)
+                        break;
+
+                if (device->ops->request)
+                        device->ops->request(device_data, i++);
+
+                vfio_device_put(device);
+
+        } while (wait_event_interruptible_timeout(vfio.release_q,
+                                                  !vfio_dev_present(group, dev),
+                                                  HZ * 10) <= 0);
 
         vfio_group_put(group);
 
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index d3204115f15d..2d67b8998fd8 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -26,6 +26,7 @@
  * @ioctl: Perform ioctl(2) on device file descriptor, supporting VFIO_DEVICE_*
  *         operations documented below
  * @mmap: Perform mmap(2) on a region of the device file descriptor
+ * @request: Request for the bus driver to release the device
  */
 struct vfio_device_ops {
         char    *name;
@@ -38,6 +39,7 @@ struct vfio_device_ops {
         long    (*ioctl)(void *device_data, unsigned int cmd,
                          unsigned long arg);
         int     (*mmap)(void *device_data, struct vm_area_struct *vma);
+        void    (*request)(void *device_data, unsigned int count);
 };
 
 extern int vfio_add_group_dev(struct device *dev,