Re: [tipc-discussion] [net v1 1/1] tipc: allow to build NACK message in link timeout function

[Jon M. <jm...@re...>]

On 7/16/20 1:13 AM, Tung Nguyen wrote:
> Commit 02288248b051 ("tipc: eliminate gap indicator from ACK messages")
> eliminated sending of the 'gap' indicator in regular ACK messages and
> only allowed to build NACK message with enabled probe/probe_reply.
> However, necessary correction for building NACK message was missed
> in tipc_link_timeout() function. This leads to significant delay and
> link reset (due to retransmission failure) in lossy environment.
>
> This commit fixes it by setting the 'probe' flag to 'true' when
> the receive deferred queue is not empty. As a result, NACK message
> will be built to send back to another peer.
>
> Fixes: commit 02288248b051 ("tipc: eliminate gap indicator from ACK messages")
> Signed-off-by: Tung Nguyen <tun...@de...>
> ---
>   net/tipc/link.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/tipc/link.c b/net/tipc/link.c
> index 263d950e70e9..d40f8e5b7683 100644
> --- a/net/tipc/link.c
> +++ b/net/tipc/link.c
> @@ -827,11 +827,11 @@ int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
>   		state |= l->bc_rcvlink->rcv_unacked;
>   		state |= l->rcv_unacked;
>   		state |= !skb_queue_empty(&l->transmq);
> -		state |= !skb_queue_empty(&l->deferdq);
>   		probe = mstate->probing;
>   		probe |= l->silent_intv_cnt;
>   		if (probe || mstate->monitoring)
>   			l->silent_intv_cnt++;
> +		probe |= !skb_queue_empty(&l->deferdq);
>   		if (l->snd_nxt == l->checkpoint) {
>   			tipc_link_update_cwin(l, 0, 0);
>   			probe = true;
Acked-by: Jon Maloy <jm...@re...>