netdevsim: Set offsets to various protocol layers

The driver periodically generates "trapped" UDP packets that it then
passes on to devlink. Set the offsets to the various protocol layers.

This is a prerequisite to the next patch, where drop monitor is taught
to check that the offset to the MAC header was set.
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/netdevsim/dev.c

@@ -374,12 +374,14 @@ static struct sk_buff *nsim_dev_trap_skb_build(void)
 		return NULL;
 	tot_len = sizeof(struct iphdr) + sizeof(struct udphdr) + data_len;
 
+	skb_reset_mac_header(skb);
 	eth = skb_put(skb, sizeof(struct ethhdr));
 	eth_random_addr(eth->h_dest);
 	eth_random_addr(eth->h_source);
 	eth->h_proto = htons(ETH_P_IP);
 	skb->protocol = htons(ETH_P_IP);
 
+	skb_set_network_header(skb, skb->len);
 	iph = skb_put(skb, sizeof(struct iphdr));
 	iph->protocol = IPPROTO_UDP;
 	iph->saddr = in_aton("192.0.2.1");
@@ -392,6 +394,7 @@ static struct sk_buff *nsim_dev_trap_skb_build(void)
 	iph->check = 0;
 	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
 
+	skb_set_transport_header(skb, skb->len);
 	udph = skb_put_zero(skb, sizeof(struct udphdr) + data_len);
 	get_random_bytes(&udph->source, sizeof(u16));
 	get_random_bytes(&udph->dest, sizeof(u16));