Re: [dpdk-dev] [PATCH v6 5/5] vhost: message handling implemented as a callback array

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Nikolay,

On 09/24/2018 10:17 PM, Nikolay Nikolaev wrote:
> Introduce vhost_message_handlers, which maps the message request
> type to the message handler. Then replace the switch construct
> with a map and call.
> 
> Failing vhost_user_set_features is fatal and all processing should
> stop immediately and propagate the error to the upper layers. Change
> the code accordingly to reflect that.
> 
> Signed-off-by: Nikolay Nikolaev <nicknickolaev@gmail.com>
> ---
>   lib/librte_vhost/vhost_user.c |  150 ++++++++++++++++-------------------------
>   1 file changed, 57 insertions(+), 93 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index e1b705fa7..f6ce8e092 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1477,6 +1477,35 @@ vhost_user_iotlb_msg(struct virtio_net **pdev, struct VhostUserMsg *msg)
>   	return VH_RESULT_OK;
>   }
>   
> +typedef int (*vhost_message_handler_t)(struct virtio_net **pdev,
> +					struct VhostUserMsg *msg);
> +static vhost_message_handler_t vhost_message_handlers[VHOST_USER_MAX] = {
> +	[VHOST_USER_NONE] = NULL,
> +	[VHOST_USER_GET_FEATURES] = vhost_user_get_features,
> +	[VHOST_USER_SET_FEATURES] = vhost_user_set_features,
> +	[VHOST_USER_SET_OWNER] = vhost_user_set_owner,
> +	[VHOST_USER_RESET_OWNER] = vhost_user_reset_owner,
> +	[VHOST_USER_SET_MEM_TABLE] = vhost_user_set_mem_table,
> +	[VHOST_USER_SET_LOG_BASE] = vhost_user_set_log_base,
> +	[VHOST_USER_SET_LOG_FD] = vhost_user_set_log_fd,
> +	[VHOST_USER_SET_VRING_NUM] = vhost_user_set_vring_num,
> +	[VHOST_USER_SET_VRING_ADDR] = vhost_user_set_vring_addr,
> +	[VHOST_USER_SET_VRING_BASE] = vhost_user_set_vring_base,
> +	[VHOST_USER_GET_VRING_BASE] = vhost_user_get_vring_base,
> +	[VHOST_USER_SET_VRING_KICK] = vhost_user_set_vring_kick,
> +	[VHOST_USER_SET_VRING_CALL] = vhost_user_set_vring_call,
> +	[VHOST_USER_SET_VRING_ERR] = vhost_user_set_vring_err,
> +	[VHOST_USER_GET_PROTOCOL_FEATURES] = vhost_user_get_protocol_features,
> +	[VHOST_USER_SET_PROTOCOL_FEATURES] = vhost_user_set_protocol_features,
> +	[VHOST_USER_GET_QUEUE_NUM] = vhost_user_get_queue_num,
> +	[VHOST_USER_SET_VRING_ENABLE] = vhost_user_set_vring_enable,
> +	[VHOST_USER_SEND_RARP] = vhost_user_send_rarp,
> +	[VHOST_USER_NET_SET_MTU] = vhost_user_net_set_mtu,
> +	[VHOST_USER_SET_SLAVE_REQ_FD] = vhost_user_set_req_fd,
> +	[VHOST_USER_IOTLB_MSG] = vhost_user_iotlb_msg,
> +};
> +
> +
>   /* return bytes# of read on success or negative val on failure. */
>   static int
>   read_vhost_message(int sockfd, struct VhostUserMsg *msg)
> @@ -1630,6 +1659,7 @@ vhost_user_msg_handler(int vid, int fd)
>   	int ret;
>   	int unlock_required = 0;
>   	uint32_t skip_master = 0;
> +	int request;
>   
>   	dev = get_device(vid);
>   	if (dev == NULL)
> @@ -1722,100 +1752,34 @@ vhost_user_msg_handler(int vid, int fd)
>   			goto skip_to_post_handle;
>   	}
>   
> -	switch (msg.request.master) {
> -	case VHOST_USER_GET_FEATURES:
> -		ret = vhost_user_get_features(&dev, &msg);
> -		send_vhost_reply(fd, &msg);
> -		break;
> -	case VHOST_USER_SET_FEATURES:
> -		ret = vhost_user_set_features(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_GET_PROTOCOL_FEATURES:
> -		ret = vhost_user_get_protocol_features(&dev, &msg);
> -		send_vhost_reply(fd, &msg);
> -		break;
> -	case VHOST_USER_SET_PROTOCOL_FEATURES:
> -		ret = vhost_user_set_protocol_features(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_OWNER:
> -		ret = vhost_user_set_owner(&dev, &msg);
> -		break;
> -	case VHOST_USER_RESET_OWNER:
> -		ret = vhost_user_reset_owner(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_MEM_TABLE:
> -		ret = vhost_user_set_mem_table(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_LOG_BASE:
> -		ret = vhost_user_set_log_base(&dev, &msg);
> -		if (ret)
> -			goto skip_to_reply;
> -		/* it needs a reply */
> -		send_vhost_reply(fd, &msg);
> -		break;
> -	case VHOST_USER_SET_LOG_FD:
> -		ret = vhost_user_set_log_fd(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_VRING_NUM:
> -		ret = vhost_user_set_vring_num(&dev, &msg);
> -		break;
> -	case VHOST_USER_SET_VRING_ADDR:
> -		ret = vhost_user_set_vring_addr(&dev, &msg);
> -		break;
> -	case VHOST_USER_SET_VRING_BASE:
> -		ret = vhost_user_set_vring_base(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_GET_VRING_BASE:
> -		ret = vhost_user_get_vring_base(&dev, &msg);
> -		if (ret)
> -			goto skip_to_reply;
> -		send_vhost_reply(fd, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_VRING_KICK:
> -		ret = vhost_user_set_vring_kick(&dev, &msg);
> -		break;
> -	case VHOST_USER_SET_VRING_CALL:
> -		ret = vhost_user_set_vring_call(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_VRING_ERR:
> -		ret = vhost_user_set_vring_err(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_GET_QUEUE_NUM:
> -		ret = vhost_user_get_queue_num(&dev, &msg);
> -		send_vhost_reply(fd, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_VRING_ENABLE:
> -		ret = vhost_user_set_vring_enable(&dev, &msg);
> -		break;
> -	case VHOST_USER_SEND_RARP:
> -		ret = vhost_user_send_rarp(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_NET_SET_MTU:
> -		ret = vhost_user_net_set_mtu(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_SET_SLAVE_REQ_FD:
> -		ret = vhost_user_set_req_fd(&dev, &msg);
> -		break;
> -
> -	case VHOST_USER_IOTLB_MSG:
> -		ret = vhost_user_iotlb_msg(&dev, &msg);
> -		break;
> +	request = msg.request.master;
> +	if (request > VHOST_USER_NONE && request < VHOST_USER_MAX) {
> +		if (!vhost_message_handlers[request])
> +			goto skip_to_post_handle;
> +		ret = vhost_message_handlers[request](&dev, &msg);

Have you tested the series?
In case ret == VH_RESULT_REPLY, like the first request (GET_FEATURES),
it fails because ret is tested as non-zero afterwards to detect
failures.

>   
> -	default:
> -		ret = -1;
> -		break;
> +		switch (ret) {
> +		case VH_RESULT_ERR:
> +			RTE_LOG(ERR, VHOST_CONFIG,
> +				"Processing %s failed.\n",
> +				vhost_message_str[request]);
> +			break;
> +		case VH_RESULT_OK:
> +			RTE_LOG(DEBUG, VHOST_CONFIG,
> +				"Processing %s succeeded.\n",
> +				vhost_message_str[request]);
> +			break;
> +		case VH_RESULT_REPLY:
> +			RTE_LOG(INFO, VHOST_CONFIG,
> +				"Processing %s succeeded and needs reply.\n",
> +				vhost_message_str[request]);
> +			send_vhost_reply(fd, &msg);
> +			break;
> +		}
> +	} else {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"Requested invalid message type %d.\n", request);
> +		ret = VH_RESULT_ERR;
>   	}
>   
>   skip_to_post_handle:
>