[PATCH v7 04/26] virtio_ring: split: extract the logic of creating vring

[Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>]

Separate the logic of split to create vring queue.

For the convenience of passing parameters, add a structure
vring_split.

This feature is required for subsequent virtuqueue reset vring.

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 74 +++++++++++++++++++++++++-----------
 1 file changed, 51 insertions(+), 23 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index b87130c8f312..d32793615451 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -85,6 +85,13 @@ struct vring_desc_extra {
 	u16 next;			/* The next desc state in a list. */
 };
 
+struct vring_split {
+	void *queue;
+	dma_addr_t dma_addr;
+	size_t queue_size_in_bytes;
+	struct vring vring;
+};
+
 struct vring_virtqueue {
 	struct virtqueue vq;
 
@@ -915,28 +922,21 @@ static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
 	return NULL;
 }
 
-static struct virtqueue *vring_create_virtqueue_split(
-	unsigned int index,
-	unsigned int num,
-	unsigned int vring_align,
-	struct virtio_device *vdev,
-	bool weak_barriers,
-	bool may_reduce_num,
-	bool context,
-	bool (*notify)(struct virtqueue *),
-	void (*callback)(struct virtqueue *),
-	const char *name)
+static int vring_create_vring_split(struct vring_split *vring,
+				    struct virtio_device *vdev,
+				    unsigned int vring_align,
+				    bool weak_barriers,
+				    bool may_reduce_num,
+				    u32 num)
 {
-	struct virtqueue *vq;
 	void *queue = NULL;
 	dma_addr_t dma_addr;
 	size_t queue_size_in_bytes;
-	struct vring vring;
 
 	/* We assume num is a power of 2. */
 	if (num & (num - 1)) {
 		dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
-		return NULL;
+		return -EINVAL;
 	}
 
 	/* TODO: allocate each queue chunk individually */
@@ -947,11 +947,11 @@ static struct virtqueue *vring_create_virtqueue_split(
 		if (queue)
 			break;
 		if (!may_reduce_num)
-			return NULL;
+			return -ENOMEM;
 	}
 
 	if (!num)
-		return NULL;
+		return -ENOMEM;
 
 	if (!queue) {
 		/* Try to get a single page. You are my only hope! */
@@ -959,21 +959,49 @@ static struct virtqueue *vring_create_virtqueue_split(
 					  &dma_addr, GFP_KERNEL|__GFP_ZERO);
 	}
 	if (!queue)
-		return NULL;
+		return -ENOMEM;
 
 	queue_size_in_bytes = vring_size(num, vring_align);
-	vring_init(&vring, num, queue, vring_align);
+	vring_init(&vring->vring, num, queue, vring_align);
+
+	vring->dma_addr = dma_addr;
+	vring->queue = queue;
+	vring->queue_size_in_bytes = queue_size_in_bytes;
+
+	return 0;
+}
+
+static struct virtqueue *vring_create_virtqueue_split(
+	unsigned int index,
+	unsigned int num,
+	unsigned int vring_align,
+	struct virtio_device *vdev,
+	bool weak_barriers,
+	bool may_reduce_num,
+	bool context,
+	bool (*notify)(struct virtqueue *),
+	void (*callback)(struct virtqueue *),
+	const char *name)
+{
+	struct vring_split vring;
+	struct virtqueue *vq;
+	int err;
+
+	err = vring_create_vring_split(&vring, vdev, vring_align, weak_barriers,
+				       may_reduce_num, num);
+	if (err)
+		return NULL;
 
-	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
+	vq = __vring_new_virtqueue(index, vring.vring, vdev, weak_barriers, context,
 				   notify, callback, name);
 	if (!vq) {
-		vring_free_queue(vdev, queue_size_in_bytes, queue,
-				 dma_addr);
+		vring_free_queue(vdev, vring.queue_size_in_bytes, vring.queue,
+				 vring.dma_addr);
 		return NULL;
 	}
 
-	to_vvq(vq)->split.queue_dma_addr = dma_addr;
-	to_vvq(vq)->split.queue_size_in_bytes = queue_size_in_bytes;
+	to_vvq(vq)->split.queue_dma_addr = vring.dma_addr;
+	to_vvq(vq)->split.queue_size_in_bytes = vring.queue_size_in_bytes;
 	to_vvq(vq)->we_own_ring = true;
 
 	return vq;
-- 
2.31.0