Re: [PATCH v11 08/40] virtio_ring: split: extract the logic of alloc queue

Jason Wang
2022-07-04T03:59:30Z

在 2022/7/1 16:45, Xuan Zhuo 写道:
> On Fri, 1 Jul 2022 16:26:25 +0800, Jason Wang <jasowang@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 <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.

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;