ipv6: add priority parameter to ip6_xmit()

Currently, ip6_xmit() sets skb->priority based on sk->sk_priority

This is not desirable for TCP since TCP shares the same ctl socket
for a given netns. We want to be able to send RST or ACK packets
with a non zero skb->priority.

This patch has no functional change.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ipv6.h

@@ -981,7 +981,7 @@ int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb);
  *	upper-layer output functions
  */
 int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
-	     __u32 mark, struct ipv6_txoptions *opt, int tclass);
+	     __u32 mark, struct ipv6_txoptions *opt, int tclass, u32 priority);
 
 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr);
 

net/dccp/ipv6.c

@@ -230,7 +230,8 @@ static int dccp_v6_send_response(const struct sock *sk, struct request_sock *req
 		opt = ireq->ipv6_opt;
 		if (!opt)
 			opt = rcu_dereference(np->opt);
-		err = ip6_xmit(sk, skb, &fl6, sk->sk_mark, opt, np->tclass);
+		err = ip6_xmit(sk, skb, &fl6, sk->sk_mark, opt, np->tclass,
+			       sk->sk_priority);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);
 	}
@@ -284,7 +285,7 @@ static void dccp_v6_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
 	dst = ip6_dst_lookup_flow(ctl_sk, &fl6, NULL);
 	if (!IS_ERR(dst)) {
 		skb_dst_set(skb, dst);
-		ip6_xmit(ctl_sk, skb, &fl6, 0, NULL, 0);
+		ip6_xmit(ctl_sk, skb, &fl6, 0, NULL, 0, 0);
 		DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 		DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
 		return;

net/ipv6/inet6_connection_sock.c

@@ -133,7 +133,7 @@ int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl_unused
 	fl6.daddr = sk->sk_v6_daddr;
 
 	res = ip6_xmit(sk, skb, &fl6, sk->sk_mark, rcu_dereference(np->opt),
-		       np->tclass);
+		       np->tclass,  sk->sk_priority);
 	rcu_read_unlock();
 	return res;
 }

net/ipv6/ip6_output.c

@@ -193,7 +193,7 @@ bool ip6_autoflowlabel(struct net *net, const struct ipv6_pinfo *np)
  * which are using proper atomic operations or spinlocks.
  */
 int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
-	     __u32 mark, struct ipv6_txoptions *opt, int tclass)
+	     __u32 mark, struct ipv6_txoptions *opt, int tclass, u32 priority)
 {
 	struct net *net = sock_net(sk);
 	const struct ipv6_pinfo *np = inet6_sk(sk);
@@ -258,7 +258,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
 	hdr->daddr = *first_hop;
 
 	skb->protocol = htons(ETH_P_IPV6);
-	skb->priority = sk->sk_priority;
+	skb->priority = priority;
 	skb->mark = mark;
 
 	mtu = dst_mtu(dst);

net/ipv6/tcp_ipv6.c

@@ -512,7 +512,8 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
 		opt = ireq->ipv6_opt;
 		if (!opt)
 			opt = rcu_dereference(np->opt);
-		err = ip6_xmit(sk, skb, fl6, sk->sk_mark, opt, np->tclass);
+		err = ip6_xmit(sk, skb, fl6, sk->sk_mark, opt, np->tclass,
+			       sk->sk_priority);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);
 	}
@@ -907,7 +908,8 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
 	dst = ip6_dst_lookup_flow(ctl_sk, &fl6, NULL);
 	if (!IS_ERR(dst)) {
 		skb_dst_set(buff, dst);
-		ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL, tclass);
+		ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL, tclass,
+			 0);
 		TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
 		if (rst)
 			TCP_INC_STATS(net, TCP_MIB_OUTRSTS);

net/sctp/ipv6.c

@@ -215,7 +215,7 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *transport)
 
 	rcu_read_lock();
 	res = ip6_xmit(sk, skb, fl6, sk->sk_mark, rcu_dereference(np->opt),
-		       tclass);
+		       tclass, sk->sk_priority);
 	rcu_read_unlock();
 	return res;
 }