Re: [PATCH] net/vhost: fix segfault when creating vdev dynamically

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

On 3/28/2018 12:05 AM, Junjie Chen wrote:
> when creating vdev dynamically, vhost pmd driver start directly without
> checking TX/RX queues ready or not, and thus cause segmentation fault when
> vhost library accessing queues. This patch add flag to check whether queues
> setup or not, and add driver start call into dev_start to allow user start
> it after setting up queue.

The issue is clear now. But this patch just puts the situation before 
below fix: "it doesn't create the actual datagram socket until you call 
.dev_start()."

To fix this issue, we might delay the queue setup until we really have 
queues?

> Fixes: aed0b12930b33("net/vhost: fix socket file deleted on stop")

Missed the space between commit number and title. And we keep 12 
characters for the commit id.

Thanks,
Jianfeng

> Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
> ---
>   drivers/net/vhost/rte_eth_vhost.c | 21 +++++++++++++++++++--
>   1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
> index 3aae01c..719a150 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -118,6 +118,7 @@ struct pmd_internal {
>   	char *iface_name;
>   	uint16_t max_queues;
>   	rte_atomic32_t started;
> +	rte_atomic32_t once;
>   };
>   
>   struct internal_list {
> @@ -772,12 +773,24 @@ rte_eth_vhost_get_vid_from_port_id(uint16_t port_id)
>   static int
>   eth_dev_start(struct rte_eth_dev *dev)
>   {
> +	int ret = 0;
>   	struct pmd_internal *internal = dev->data->dev_private;
>   
> +	if (unlikely(rte_atomic32_read(&internal->once) == 0)) {
> +		ret = rte_vhost_driver_start(internal->iface_name);
> +		if (ret < 0) {
> +			RTE_LOG(ERR, PMD, "Failed to start driver for %s\n",
> +				internal->iface_name);
> +			return ret;
> +		}
> +
> +		rte_atomic32_set(&internal->once, 1);
> +	}
> +
>   	rte_atomic32_set(&internal->started, 1);
>   	update_queuing_status(dev);
>   
> -	return 0;
> +	return ret;
>   }
>   
>   static void
> @@ -1101,7 +1114,11 @@ eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
>   		goto error;
>   	}
>   
> -	if (rte_vhost_driver_start(iface_name) < 0) {
> +	if (!data->rx_queues || !data->tx_queues) {
> +		RTE_LOG(INFO, PMD,
> +			"TX/RX queue is not ready, driver will not start\n");
> +		rte_atomic32_set(&internal->once, 0);
> +	} else if (rte_vhost_driver_start(iface_name) < 0) {
>   		RTE_LOG(ERR, PMD, "Failed to start driver for %s\n",
>   			iface_name);
>   		goto error;