l2tp: do data sequence number handling in a separate func

This change moves some code handling data sequence numbers into a
separate function to avoid too much indentation. This is to prepare
for some changes to data sequence number handling in subsequent
patches.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 20 deletions

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 6984c3a353cd..5ca29659171d 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -542,6 +542,38 @@ static inline int l2tp_verify_udp_checksum(struct sock *sk,
         return __skb_checksum_complete(skb);
 }
 
+/* If packet has sequence numbers, queue it if acceptable. Returns 0 if
+ * acceptable, else non-zero.
+ */
+static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
+{
+        if (session->reorder_timeout != 0) {
+                /* Packet reordering enabled. Add skb to session's
+                 * reorder queue, in order of ns.
+                 */
+                l2tp_recv_queue_skb(session, skb);
+        } else {
+                /* Packet reordering disabled. Discard out-of-sequence
+                 * packets
+                 */
+                if (L2TP_SKB_CB(skb)->ns != session->nr) {
+                        atomic_long_inc(&session->stats.rx_seq_discards);
+                        l2tp_dbg(session, L2TP_MSG_SEQ,
+                                 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
+                                 session->name, L2TP_SKB_CB(skb)->ns,
+                                 L2TP_SKB_CB(skb)->length, session->nr,
+                                 skb_queue_len(&session->reorder_q));
+                        goto discard;
+                }
+                skb_queue_tail(&session->reorder_q, skb);
+        }
+
+        return 0;
+
+discard:
+        return 1;
+}
+
 /* Do receive processing of L2TP data frames. We handle both L2TPv2
  * and L2TPv3 data frames here.
  *
@@ -757,26 +789,8 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
          * enabled. Saved L2TP protocol info is stored in skb->sb[].
          */
         if (L2TP_SKB_CB(skb)->has_seq) {
-                if (session->reorder_timeout != 0) {
-                        /* Packet reordering enabled. Add skb to session's
-                         * reorder queue, in order of ns.
-                         */
-                        l2tp_recv_queue_skb(session, skb);
-                } else {
-                        /* Packet reordering disabled. Discard out-of-sequence
-                         * packets
-                         */
-                        if (L2TP_SKB_CB(skb)->ns != session->nr) {
-                                atomic_long_inc(&session->stats.rx_seq_discards);
-                                l2tp_dbg(session, L2TP_MSG_SEQ,
-                                         "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
-                                         session->name, L2TP_SKB_CB(skb)->ns,
-                                         L2TP_SKB_CB(skb)->length, session->nr,
-                                         skb_queue_len(&session->reorder_q));
-                                goto discard;
-                        }
-                        skb_queue_tail(&session->reorder_q, skb);
-                }
+                if (l2tp_recv_data_seq(session, skb))
+                        goto discard;
         } else {
                 /* No sequence numbers. Add the skb to the tail of the
                  * reorder queue. This ensures that it will be