[PATCH v4 2/2] examples/vhost: unconfigure DMA vchannel

[Maxime Coquelin]

On 10/13/22 08:40, xuan.ding at intel.com wrote:
> From: Xuan Ding <xuan.ding at intel.com>
> 
> This patch applies rte_vhost_async_dma_unconfigure() to manually
> free DMA vchannels. Before unconfiguration, need make sure the
> specified DMA device is no longer used by any vhost ports.
> 
> Signed-off-by: Xuan Ding <xuan.ding at intel.com>
> ---
>   examples/vhost/main.c | 38 +++++++++++++++++++++++++-------------
>   1 file changed, 25 insertions(+), 13 deletions(-)
> 
> diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> index ac78704d79..bfeb808dcc 100644
> --- a/examples/vhost/main.c
> +++ b/examples/vhost/main.c
> @@ -73,6 +73,7 @@ static int total_num_mbufs = NUM_MBUFS_DEFAULT;
>   
>   struct dma_for_vhost dma_bind[RTE_MAX_VHOST_DEVICE];
>   int16_t dmas_id[RTE_DMADEV_DEFAULT_MAX];
> +int16_t dma_ref_count[RTE_DMADEV_DEFAULT_MAX];
>   static int dma_count;
>   
>   /* mask of enabled ports */
> @@ -371,6 +372,7 @@ open_dma(const char *value)
>   done:
>   		(dma_info + socketid)->dmas[vring_id].dev_id = dev_id;
>   		(dma_info + socketid)->async_flag |= async_flag;
> +		dma_ref_count[dev_id]++;
>   		i++;
>   	}
>   out:
> @@ -1562,6 +1564,27 @@ vhost_clear_queue(struct vhost_dev *vdev, uint16_t queue_id)
>   	}
>   }
>   
> +static void
> +vhost_clear_async(struct vhost_dev *vdev, int vid, uint16_t queue_id)
> +{
> +	int16_t dma_id;
> +
> +	if (dma_bind[vid].dmas[queue_id].async_enabled) {

if (!dma_bind[vid].dmas[queue_id].async_enabled)
	return;

> +		vhost_clear_queue(vdev, queue_id);
> +		rte_vhost_async_channel_unregister(vid, queue_id);
> +		dma_bind[vid].dmas[queue_id].async_enabled = false;
> +
> +		dma_id = dma_bind[vid2socketid[vdev->vid]].dmas[queue_id].dev_id;
> +		dma_ref_count[dma_id]--;
> +
> +		if (dma_ref_count[dma_id] == 0) {

if (dma_ref_count[dma_id] > 0)
	return;

Doing this should improve readability.

> +			if (rte_vhost_async_dma_unconfigure(dma_id, 0) < 0)
> +				RTE_LOG(ERR, VHOST_CONFIG,
> +				       "Failed to unconfigure DMA %d in vhost.\n", dma_id);
> +		}
> +	}
> +}
> +
>   /*
>    * Remove a device from the specific data core linked list and from the
>    * main linked list. Synchronization  occurs through the use of the
> @@ -1618,17 +1641,8 @@ destroy_device(int vid)
>   		"(%d) device has been removed from data core\n",
>   		vdev->vid);
>   
> -	if (dma_bind[vid].dmas[VIRTIO_RXQ].async_enabled) {
> -		vhost_clear_queue(vdev, VIRTIO_RXQ);
> -		rte_vhost_async_channel_unregister(vid, VIRTIO_RXQ);
> -		dma_bind[vid].dmas[VIRTIO_RXQ].async_enabled = false;
> -	}
> -
> -	if (dma_bind[vid].dmas[VIRTIO_TXQ].async_enabled) {
> -		vhost_clear_queue(vdev, VIRTIO_TXQ);
> -		rte_vhost_async_channel_unregister(vid, VIRTIO_TXQ);
> -		dma_bind[vid].dmas[VIRTIO_TXQ].async_enabled = false;
> -	}
> +	vhost_clear_async(vdev, vid, VIRTIO_RXQ);
> +	vhost_clear_async(vdev, vid, VIRTIO_TXQ);
>   
>   	rte_free(vdev);
>   }
> @@ -1690,8 +1704,6 @@ vhost_async_channel_register(int vid)
>   	return rx_ret | tx_ret;
>   }
>   
> -
> -
>   /*
>    * A new device is added to a data core. First the device is added to the main linked list
>    * and then allocated to a specific data core.