virtio: virtio_break_device() to mark all virtqueues broken.

Good for post-apocalyptic scenarios, like S/390 hotplug.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 17 insertions, 0 deletions

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 1e443629f76d..4d08f45a9c29 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -865,4 +865,19 @@ bool virtqueue_is_broken(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_is_broken);
 
+/*
+ * This should prevent the device from being used, allowing drivers to
+ * recover.  You may need to grab appropriate locks to flush.
+ */
+void virtio_break_device(struct virtio_device *dev)
+{
+	struct virtqueue *_vq;
+
+	list_for_each_entry(_vq, &dev->vqs, list) {
+		struct vring_virtqueue *vq = to_vvq(_vq);
+		vq->broken = true;
+	}
+}
+EXPORT_SYMBOL_GPL(virtio_break_device);
+
 MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index e4abb84199be..b46671e28de2 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -106,6 +106,8 @@ static inline struct virtio_device *dev_to_virtio(struct device *_dev)
 int register_virtio_device(struct virtio_device *dev);
 void unregister_virtio_device(struct virtio_device *dev);
 
+void virtio_break_device(struct virtio_device *dev);
+
 /**
  * virtio_driver - operations for a virtio I/O driver
  * @driver: underlying device driver (populate name and owner).