On Fri, 1 Jul 2022 16:26:25 +0800, Jason Wang [off-list ref] wrote:

在 2022/6/29 14:56, Xuan Zhuo 写道:

quoted

Separate the logic of split to create vring queue.

This feature is required for subsequent virtuqueue reset vring.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
  drivers/virtio/virtio_ring.c | 68 ++++++++++++++++++++++--------------
  1 file changed, 42 insertions(+), 26 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 49d61e412dc6..a9ceb9c16c54 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c

@@ -949,28 +949,19 @@ static void vring_free_split(struct vring_virtqueue_split *vring,
  	kfree(vring->desc_extra);
  }

-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_alloc_queue_split(struct vring_virtqueue_split *vring,
+				   struct virtio_device *vdev,
+				   u32 num,
+				   unsigned int vring_align,
+				   bool may_reduce_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 */

@@ -981,11 +972,11 @@ 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! */

@@ -993,21 +984,46 @@ static struct virtqueue *vring_create_virtqueue_split(
  					  &dma_addr, GFP_KERNEL|__GFP_ZERO);
  	}
  	if (!queue)
-		return NULL;
+		return -ENOMEM;
+
+	vring_init(&vring->vring, num, queue, vring_align);

-	queue_size_in_bytes = vring_size(num, vring_align);
-	vring_init(&vring, num, queue, vring_align);
+	vring->queue_dma_addr = dma_addr;
+	vring->queue_size_in_bytes = vring_size(num, vring_align);
+
+	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_virtqueue_split vring = {};
+	struct virtqueue *vq;
+	int err;
+
+	err = vring_alloc_queue_split(&vring, vdev, num, vring_align,
+				      may_reduce_num);
+	if (err)
+		return NULL;

-	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
-				   notify, callback, name);
+	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_split(&vring, vdev);
  		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.queue_dma_addr;

Nit: having two queue_dma_addr seems redundant (so did queue_size_in_bytes).

two?

Where is the problem I don't understand?

Thanks.

Thanks

quoted

+	to_vvq(vq)->split.queue_size_in_bytes = vring.queue_size_in_bytes;
  	to_vvq(vq)->we_own_ring = true;

  	return vq;