ipvs: clear skb->tstamp in forwarding path

fq qdisc requires tstamp to be cleared in forwarding path

Reported-by: Evgeny B <abt-admin@mail.ru>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=209427
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Fixes: 8203e2d844 ("net: clear skb->tstamp in forwarding paths")
Fixes: fb420d5d91 ("tcp/fq: move back to CLOCK_MONOTONIC")
Fixes: 80b14dee2b ("net: Add a new socket option for a future transmit time.")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipvs/ip_vs_xmit.c

@@ -609,6 +609,8 @@ static inline int ip_vs_tunnel_xmit_prepare(struct sk_buff *skb,
 	if (ret == NF_ACCEPT) {
 		nf_reset_ct(skb);
 		skb_forward_csum(skb);
+		if (skb->dev)
+			skb->tstamp = 0;
 	}
 	return ret;
 }
@@ -649,6 +651,8 @@ static inline int ip_vs_nat_send_or_cont(int pf, struct sk_buff *skb,
 
 	if (!local) {
 		skb_forward_csum(skb);
+		if (skb->dev)
+			skb->tstamp = 0;
 		NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
 			NULL, skb_dst(skb)->dev, dst_output);
 	} else
@@ -669,6 +673,8 @@ static inline int ip_vs_send_or_cont(int pf, struct sk_buff *skb,
 	if (!local) {
 		ip_vs_drop_early_demux_sk(skb);
 		skb_forward_csum(skb);
+		if (skb->dev)
+			skb->tstamp = 0;
 		NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
 			NULL, skb_dst(skb)->dev, dst_output);
 	} else