[PATCH v9 17/32] virtio_ring: packed: introduce virtqueue_resize_packed()

[Xuan Zhuo]

virtio ring packed supports resize.

Only after the new vring is successfully allocated based on the new num,
we will release the old vring. In any case, an error is returned,
indicating that the vring still points to the old vring.

In the case of an error, the caller must re-initialize(by
virtqueue_reinit_packed()) the virtqueue to ensure that the vring can be
used.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 40 ++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 9a4f2db718bd..06f66b15c86c 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2059,6 +2059,46 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	return NULL;
 }
 
+static int virtqueue_resize_packed(struct virtqueue *_vq, u32 num)
+{
+	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
+	struct vring_packed_desc_event *driver, *device;
+	size_t ring_size_in_bytes, event_size_in_bytes;
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct virtio_device *vdev = _vq->vdev;
+	struct vring_desc_state_packed *state;
+	struct vring_desc_extra *extra;
+	struct vring_packed_desc *ring;
+	int err;
+
+	if (vring_alloc_queue_packed(vdev, num, &ring, &driver, &device,
+				     &ring_dma_addr, &driver_event_dma_addr,
+				     &device_event_dma_addr,
+				     &ring_size_in_bytes, &event_size_in_bytes))
+		goto err_ring;
+
+
+	err = vring_alloc_state_extra_packed(num, &state, &extra);
+	if (err)
+		goto err_state_extra;
+
+	vring_free(&vq->vq);
+
+	vring_virtqueue_attach_packed(vq, num, ring, driver, device,
+				      ring_dma_addr, driver_event_dma_addr,
+				      device_event_dma_addr, ring_size_in_bytes,
+				      event_size_in_bytes, state, extra);
+	vring_virtqueue_init_packed(vq, vdev);
+	return 0;
+
+err_state_extra:
+	vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
+	vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
+	vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
+err_ring:
+	return -ENOMEM;
+}
+
 
 /*
  * Generic functions and exported symbols.
-- 
2.31.0