Re: [PATCH v1] net/vhost: add queue status check

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

On 11/16/21 17:44, Miao Li wrote:
> This patch adds queue status check to make sure that vhost monitor
> address will not be got until the link between backend and frontend
s/got/gone/?
> up and the packets are allowed to be queued.

It needs a fixes tag.

> Signed-off-by: Miao Li <miao.li@intel.com>
> ---
>   drivers/net/vhost/rte_eth_vhost.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
> index 070f0e6dfd..9d600054d8 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -1415,6 +1415,8 @@ vhost_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
>   	int ret;
>   	if (vq == NULL)
>   		return -EINVAL;
> +	if (unlikely(rte_atomic32_read(&vq->allow_queuing) == 0))
> +		return -EINVAL;

How does it help?
What does prevent allow_queuing to become zero between the check and the
call to rte_vhost_get_monitor_addr?

I think you need to implement the same logic as in eth_vhost_rx(), i.e.
check allow_queueing, set while_queueing, check allow_queueing, do your
stuff and clear while_queuing.

>   	ret = rte_vhost_get_monitor_addr(vq->vid, vq->virtqueue_id,
>   			&vhost_pmc);
>   	if (ret < 0)
> 

Maxime