Re: [PATCH] virtio-net: purge queued rx packets on queue deletion

[Jason Wang]

On 2020/11/12 下午5:46, Yuri Benditovich wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1829272
> When deleting queue pair, purge pending RX packets if any.
> Example of problematic flow:
> 1. Bring up q35 VM with tap (vhost off) and virtio-net or e1000e
> 2. Run ping flood to the VM NIC ( 1 ms interval)
> 3. Hot unplug the NIC device (device_del)
>     During unplug process one or more packets come, the NIC
>     can't receive, tap disables read_poll
> 4. Hot plug the device (device_add) with the same netdev
> The tap stays with read_poll disabled and does not receive
> any packets anymore (tap_send never triggered)
>
> Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>


Applied.

Thanks


> ---
>   net/net.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/net/net.c b/net/net.c
> index 7a2a0fb5ac..a95b417300 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -411,10 +411,14 @@ void qemu_del_nic(NICState *nic)
>   
>       qemu_macaddr_set_free(&nic->conf->macaddr);
>   
> -    /* If this is a peer NIC and peer has already been deleted, free it now. */
> -    if (nic->peer_deleted) {
> -        for (i = 0; i < queues; i++) {
> -            qemu_free_net_client(qemu_get_subqueue(nic, i)->peer);
> +    for (i = 0; i < queues; i++) {
> +        NetClientState *nc = qemu_get_subqueue(nic, i);
> +        /* If this is a peer NIC and peer has already been deleted, free it 
> now. */
> +        if (nic->peer_deleted) {
> +            qemu_free_net_client(nc->peer);
> +        } else if (nc->peer) {
> +            /* if there are RX packets pending, complete them */
> +            qemu_purge_queued_packets(nc->peer);
>           }
>       }
>