Re: [PATCH v8 11/16] virtio_ring: packed: extract the logic of alloc queue

[Jason Wang <jasowang@xxxxxxxxxx>]

在 2022/3/14 下午5:34, 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 | 121 ++++++++++++++++++++++++++---------
>   1 file changed, 92 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index a15869514146..96ff2dabda14 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -85,6 +85,18 @@ struct vring_desc_extra {
>   	u16 next;			/* The next desc state in a list. */
>   };
>   
> +struct vring_packed {
> +	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;
> +};
> +


Interesting,  a nitpick here is that if it is only used by one helper, 
it's probably not worth to bother.

And if we want to do that, we need

1) use a separated patch

2) do it for split virtqueue as well

Thanks


>   struct vring_virtqueue {
>   	struct virtqueue vq;
>   
> @@ -1735,45 +1747,101 @@ 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 void vring_free_vring_packed(struct vring_packed *vring,
> +				    struct virtio_device *vdev)
> +{
> +	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;
> +
> +	ring                  = vring->ring;
> +	driver                = vring->driver;
> +	device                = vring->device;
> +	ring_size_in_bytes    = vring->ring_size_in_bytes;
> +	event_size_in_bytes   = vring->event_size_in_bytes;
> +	ring_dma_addr         = vring->ring_dma_addr;
> +	driver_event_dma_addr = vring->driver_event_dma_addr;
> +	device_event_dma_addr = vring->device_event_dma_addr;
> +
> +	if (device)
> +		vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
> +
> +	if (driver)
> +		vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
> +
> +	if (ring)
> +		vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
> +}
> +
> +static int vring_alloc_queue_packed(struct vring_packed *vring,
> +				    struct virtio_device *vdev,
> +				    u32 num)
>   {
> -	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;
>   	size_t ring_size_in_bytes, event_size_in_bytes;
>   
> +	memset(vring, 0, sizeof(*vring));
> +
>   	ring_size_in_bytes = num * sizeof(struct vring_packed_desc);
>   
>   	ring = vring_alloc_queue(vdev, ring_size_in_bytes,
>   				 &ring_dma_addr,
>   				 GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
>   	if (!ring)
> -		goto err_ring;
> +		goto err;
> +
> +	vring->num = num;
> +	vring->ring = ring;
> +	vring->ring_size_in_bytes = ring_size_in_bytes;
> +	vring->ring_dma_addr = ring_dma_addr;
>   
>   	event_size_in_bytes = sizeof(struct vring_packed_desc_event);
> +	vring->event_size_in_bytes = event_size_in_bytes;
>   
>   	driver = vring_alloc_queue(vdev, event_size_in_bytes,
>   				   &driver_event_dma_addr,
>   				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
>   	if (!driver)
> -		goto err_driver;
> +		goto err;
> +
> +	vring->driver = driver;
> +	vring->driver_event_dma_addr = driver_event_dma_addr;
>   
>   	device = vring_alloc_queue(vdev, event_size_in_bytes,
>   				   &device_event_dma_addr,
>   				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
>   	if (!device)
> -		goto err_device;
> +		goto err;
> +
> +	vring->device = device;
> +	vring->device_event_dma_addr = device_event_dma_addr;
> +	return 0;
> +
> +err:
> +	vring_free_vring_packed(vring, vdev);
> +	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)
> +{
> +	struct vring_virtqueue *vq;
> +	struct vring_packed vring;
> +
> +	if (vring_alloc_queue_packed(&vring, vdev, num))
> +		goto err_vq;
>   
>   	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
>   	if (!vq)
> @@ -1805,17 +1873,17 @@ static struct virtqueue *vring_create_virtqueue_packed(
>   	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
>   		vq->weak_barriers = false;
>   
> -	vq->packed.ring_dma_addr = ring_dma_addr;
> -	vq->packed.driver_event_dma_addr = driver_event_dma_addr;
> -	vq->packed.device_event_dma_addr = device_event_dma_addr;
> +	vq->packed.ring_dma_addr = vring.ring_dma_addr;
> +	vq->packed.driver_event_dma_addr = vring.driver_event_dma_addr;
> +	vq->packed.device_event_dma_addr = vring.device_event_dma_addr;
>   
> -	vq->packed.ring_size_in_bytes = ring_size_in_bytes;
> -	vq->packed.event_size_in_bytes = event_size_in_bytes;
> +	vq->packed.ring_size_in_bytes = vring.ring_size_in_bytes;
> +	vq->packed.event_size_in_bytes = vring.event_size_in_bytes;
>   
>   	vq->packed.vring.num = num;
> -	vq->packed.vring.desc = ring;
> -	vq->packed.vring.driver = driver;
> -	vq->packed.vring.device = device;
> +	vq->packed.vring.desc = vring.ring;
> +	vq->packed.vring.driver = vring.driver;
> +	vq->packed.vring.device = vring.device;
>   
>   	vq->packed.next_avail_idx = 0;
>   	vq->packed.avail_wrap_counter = 1;
> @@ -1856,12 +1924,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
>   err_desc_state:
>   	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:
> +	vring_free_vring_packed(&vring, vdev);
>   	return NULL;
>   }
>   

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