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

Jason Wang
2022-04-12T06:28:47Z

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@linux.alibaba.com>
> ---
> 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;