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

Xuan Zhuo
Fri, 01 Jul 2022 08:45:58 -0000

On Fri, 1 Jul 2022 16:26:25 +0800, Jason Wang <jasowang at redhat.com>
wrote:
>
> ? 2022/6/29 14:56, Xuan Zhuo ??:
> > Separate the logic of split to create vring queue.
> >
> > This feature is required for subsequent virtuqueue reset vring.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo at 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
>
>
> > +	to_vvq(vq)->split.queue_size_in_bytes =
vring.queue_size_in_bytes;
> >   	to_vvq(vq)->we_own_ring = true;
> >
> >   	return vq;
>