[RFC PATCH v2 4/9] vhost: fix async access

[Maxime Coquelin]

Hi Jiayu,

On 3/30/22 15:49, David Marchand wrote:
> vq->async accesses must be protected with vq->access_lock.
> 
> Fixes: eb666d24085f ("vhost: fix async unregister deadlock")
> Fixes: 0c0935c5f794 ("vhost: allow to check in-flight packets for async vhost")
> Cc: stable at dpdk.org
> 
> Signed-off-by: David Marchand <david.marchand at redhat.com>
> ---
>   lib/vhost/vhost.c | 25 ++++++++++---------------
>   1 file changed, 10 insertions(+), 15 deletions(-)

Could you please test and review below patch?
We may want to apply it early, before the annotation series is applied.

Thanks!
Maxime

> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
> index 2f96a28dac..a93e41f314 100644
> --- a/lib/vhost/vhost.c
> +++ b/lib/vhost/vhost.c
> @@ -1753,27 +1753,23 @@ rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
>   	if (vq == NULL)
>   		return ret;
>   
> -	ret = 0;
> -
> -	if (!vq->async)
> -		return ret;
> -
>   	if (!rte_spinlock_trylock(&vq->access_lock)) {
>   		VHOST_LOG_CONFIG(ERR, "(%s) failed to unregister async channel, virtqueue busy.\n",
>   				dev->ifname);
> -		return -1;
> +		return ret;
>   	}
>   
> -	if (vq->async->pkts_inflight_n) {
> +	if (!vq->async) {
> +		ret = 0;
> +	} else if (vq->async->pkts_inflight_n) {
>   		VHOST_LOG_CONFIG(ERR, "(%s) failed to unregister async channel.\n", dev->ifname);
>   		VHOST_LOG_CONFIG(ERR, "(%s) inflight packets must be completed before unregistration.\n",
>   			dev->ifname);
> -		ret = -1;
> -		goto out;
> +	} else {
> +		vhost_free_async_mem(vq);
> +		ret = 0;
>   	}
>   
> -	vhost_free_async_mem(vq);
> -out:
>   	rte_spinlock_unlock(&vq->access_lock);
>   
>   	return ret;
> @@ -1891,9 +1887,6 @@ rte_vhost_async_get_inflight(int vid, uint16_t queue_id)
>   	if (vq == NULL)
>   		return ret;
>   
> -	if (!vq->async)
> -		return ret;
> -
>   	if (!rte_spinlock_trylock(&vq->access_lock)) {
>   		VHOST_LOG_CONFIG(DEBUG,
>   			"(%s) failed to check in-flight packets. virtqueue busy.\n",
> @@ -1901,7 +1894,9 @@ rte_vhost_async_get_inflight(int vid, uint16_t queue_id)
>   		return ret;
>   	}
>   
> -	ret = vq->async->pkts_inflight_n;
> +	if (vq->async)
> +		ret = vq->async->pkts_inflight_n;
> +
>   	rte_spinlock_unlock(&vq->access_lock);
>   
>   	return ret;