Re: [PATCH v9 12/32] virtio_ring: packed: extract the logic of alloc queue

[Jason Wang <jasowang@xxxxxxxxxx>]

在 2022/4/6 上午11:43, Xuan Zhuo 写道:
> Separate the logic of packed to create vring queue.
>
> For the convenience of passing parameters, add a structure
> vring_packed.
>
> This feature is required for subsequent virtuqueue reset vring.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
>   drivers/virtio/virtio_ring.c | 70 ++++++++++++++++++++++++++++--------
>   1 file changed, 56 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 33864134a744..ea451ae2aaef 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -1817,19 +1817,17 @@ static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num)
>   	return desc_extra;
>   }
>   
> -static struct virtqueue *vring_create_virtqueue_packed(
> -	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_packed(struct virtio_device *vdev,
> +				    u32 num,
> +				    struct vring_packed_desc **_ring,
> +				    struct vring_packed_desc_event **_driver,
> +				    struct vring_packed_desc_event **_device,
> +				    dma_addr_t *_ring_dma_addr,
> +				    dma_addr_t *_driver_event_dma_addr,
> +				    dma_addr_t *_device_event_dma_addr,
> +				    size_t *_ring_size_in_bytes,
> +				    size_t *_event_size_in_bytes)
>   {
> -	struct vring_virtqueue *vq;
>   	struct vring_packed_desc *ring;
>   	struct vring_packed_desc_event *driver, *device;
>   	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
> @@ -1857,6 +1855,52 @@ static struct virtqueue *vring_create_virtqueue_packed(
>   	if (!device)
>   		goto err_device;
>   
> +	*_ring                   = ring;
> +	*_driver                 = driver;
> +	*_device                 = device;
> +	*_ring_dma_addr          = ring_dma_addr;
> +	*_driver_event_dma_addr  = driver_event_dma_addr;
> +	*_device_event_dma_addr  = device_event_dma_addr;
> +	*_ring_size_in_bytes     = ring_size_in_bytes;
> +	*_event_size_in_bytes    = event_size_in_bytes;


I wonder if we can simply factor out split and packed from struct 
vring_virtqueue:

struct vring_virtqueue {
    union {
        struct {} split;
        struct {} packed;
    };
};

to

struct vring_virtqueue_split {};
struct vring_virtqueue_packed {};

Then we can do things like:

vring_create_virtqueue_packed(struct virtio_device *vdev, u32 num, 
struct vring_virtqueue_packed *packed);

and

vring_vritqueue_attach_packed(struct vring_virtqueue *vq, struct 
vring_virtqueue_packed packed);

Thanks


> +
> +	return 0;
> +
> +err_device:
> +	vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
> +
> +err_driver:
> +	vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
> +
> +err_ring:
> +	return -ENOMEM;
> +}
> +
> +static struct virtqueue *vring_create_virtqueue_packed(
> +	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)
> +{
> +	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
> +	struct vring_packed_desc_event *driver, *device;
> +	size_t ring_size_in_bytes, event_size_in_bytes;
> +	struct vring_packed_desc *ring;
> +	struct vring_virtqueue *vq;
> +
> +	if (vring_alloc_queue_packed(vdev, num, &ring, &driver, &device,
> +				     &ring_dma_addr, &driver_event_dma_addr,
> +				     &device_event_dma_addr,
> +				     &ring_size_in_bytes,
> +				     &event_size_in_bytes))
> +		goto err_ring;
> +
>   	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
>   	if (!vq)
>   		goto err_vq;
> @@ -1939,9 +1983,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
>   	kfree(vq);
>   err_vq:
>   	vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
> -err_device:
>   	vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
> -err_driver:
>   	vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
>   err_ring:
>   	return NULL;