在 2022/7/1 16:45, Xuan Zhuo 写道:
On Fri, 1 Jul 2022 16:26:25 +0800, Jason Wang <jasow...@redhat.com> wrote:
在 2022/6/29 14:56, Xuan Zhuo 写道:
Separate the logic of split to create vring queue.

This feature is required for subsequent virtuqueue reset vring.

Signed-off-by: Xuan Zhuo <xuanz...@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.


I meant we had:

        vring.vring = _vring;

in __vring_new_virtqueue().

This means we'd better initialize vring fully before that?

E.g

vring.queue_dma_addr = dma_addr;

...

__vring_new_virtqueue()

Thanks



Thanks


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

        return vq;


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