ipv6: add new struct ipcm6_cookie

In the sendmsg function of UDP, raw, ICMP and l2tp sockets, we use local
variables like hlimits, tclass, opt and dontfrag and pass them to corresponding
functions like ip6_make_skb, ip6_append_data and xxx_push_pending_frames.
This is not a good practice and makes it hard to add new parameters.
This fix introduces a new struct ipcm6_cookie similar to ipcm_cookie in
ipv4 and include the above mentioned variables. And we only pass the
pointer to this structure to corresponding functions. This makes it easier
to add new parameters in the future and makes the function cleaner.

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index 46e0726..c6f5df1b 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -495,10 +495,8 @@
 	struct dst_entry *dst = NULL;
 	struct flowi6 fl6;
 	struct sockcm_cookie sockc_unused = {0};
+	struct ipcm6_cookie ipc6;
 	int addr_len = msg->msg_namelen;
-	int hlimit = -1;
-	int tclass = -1;
-	int dontfrag = -1;
 	int transhdrlen = 4; /* zero session-id */
 	int ulen = len + transhdrlen;
 	int err;
@@ -520,6 +518,10 @@
 
 	fl6.flowi6_mark = sk->sk_mark;
 
+	ipc6.hlimit = -1;
+	ipc6.tclass = -1;
+	ipc6.dontfrag = -1;
+
 	if (lsa) {
 		if (addr_len < SIN6_LEN_RFC2133)
 			return -EINVAL;
@@ -564,11 +566,11 @@
 		opt = &opt_space;
 		memset(opt, 0, sizeof(struct ipv6_txoptions));
 		opt->tot_len = sizeof(struct ipv6_txoptions);
+		ipc6.opt = opt;
 
-                err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
-                                            &hlimit, &tclass, &dontfrag,
-                                            &sockc_unused);
-                if (err < 0) {
+		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
+					    &sockc_unused);
+		if (err < 0) {
 			fl6_sock_release(flowlabel);
 			return err;
 		}
@@ -588,6 +590,7 @@
 	if (flowlabel)
 		opt = fl6_merge_options(&opt_space, flowlabel, opt);
 	opt = ipv6_fixup_options(&opt_space, opt);
+	ipc6.opt = opt;
 
 	fl6.flowi6_proto = sk->sk_protocol;
 	if (!ipv6_addr_any(daddr))
@@ -612,14 +615,14 @@
 		goto out;
 	}
 
-	if (hlimit < 0)
-		hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
+	if (ipc6.hlimit < 0)
+		ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 
-	if (tclass < 0)
-		tclass = np->tclass;
+	if (ipc6.tclass < 0)
+		ipc6.tclass = np->tclass;
 
-	if (dontfrag < 0)
-		dontfrag = np->dontfrag;
+	if (ipc6.dontfrag < 0)
+		ipc6.dontfrag = np->dontfrag;
 
 	if (msg->msg_flags & MSG_CONFIRM)
 		goto do_confirm;
@@ -627,9 +630,9 @@
 back_from_confirm:
 	lock_sock(sk);
 	err = ip6_append_data(sk, ip_generic_getfrag, msg,
-			      ulen, transhdrlen, hlimit, tclass, opt,
+			      ulen, transhdrlen, &ipc6,
 			      &fl6, (struct rt6_info *)dst,
-			      msg->msg_flags, dontfrag, &sockc_unused);
+			      msg->msg_flags, &sockc_unused);
 	if (err)
 		ip6_flush_pending_frames(sk);
 	else if (!(msg->msg_flags & MSG_MORE))