[PATCH v10 12/41] virtio_ring: split: extract the logic of attach vring

[Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>]

Separate the logic of attach vring, subsequent patches will call it
separately.

Since the "struct vring_virtqueue_split split" is created on the
stack and has been initialized to 0. So using
split->queue_dma_addr/split->queue_size_in_bytes assignment for
queue_dma_addr/queue_size_in_bytes can keep the same as the original
code.

On the other hand, subsequent patches can use the "struct
vring_virtqueue_split split" obtained by vring_alloc_queue_split() to
directly complete the attach operation.

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index ef775154536e..7ee8dd4328ca 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -935,6 +935,18 @@ static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
 	return NULL;
 }
 
+static void virtqueue_vring_attach_split(struct vring_virtqueue *vq,
+					 struct vring_virtqueue_split *vring)
+{
+	vq->split.queue_dma_addr = vring->queue_dma_addr;
+	vq->split.queue_size_in_bytes = vring->queue_size_in_bytes;
+
+	vq->split.vring = vring->vring;
+
+	vq->split.desc_state = vring->desc_state;
+	vq->split.desc_extra = vring->desc_extra;
+}
+
 static int vring_alloc_state_extra_split(struct vring_virtqueue_split *vring)
 {
 	struct vring_desc_state_split *state;
@@ -2252,10 +2264,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
 		!context;
 
-	vq->split.queue_dma_addr = 0;
-	vq->split.queue_size_in_bytes = 0;
-
-	vq->split.vring = _vring;
 	vq->split.avail_flags_shadow = 0;
 	vq->split.avail_idx_shadow = 0;
 
@@ -2275,10 +2283,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 		return NULL;
 	}
 
-	vq->split.desc_state = vring.desc_state;
-	vq->split.desc_extra = vring.desc_extra;
-
 	virtqueue_init(vq, vring.vring.num);
+	virtqueue_vring_attach_split(vq, &vring);
 
 	spin_lock(&vdev->vqs_list_lock);
 	list_add_tail(&vq->vq.list, &vdev->vqs);
-- 
2.31.0