tipc: simplify packet sequence number handling

Although the sequence number in the TIPC protocol is 16 bits, we have
until now stored it internally as an unsigned 32 bits integer.
We got around this by always doing explicit modulo-65535 operations
whenever we need to access a sequence number.

We now make the incoming and outgoing sequence numbers to unsigned
16-bit integers, and remove the modulo operations where applicable.

We also move the arithmetic inline functions for 16 bit integers
to core.h, and the function buf_seqno() to msg.h, so they can easily
be accessed from anywhere in the code.

Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 19 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index d71e83d0959b..391a96f0efc7 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -685,9 +685,9 @@ int __tipc_link_xmit(struct net *net, struct tipc_link *link,
 	unsigned int maxwin = link->window;
 	unsigned int imp = msg_importance(msg);
 	uint mtu = link->mtu;
-	uint ack = mod(link->next_in_no - 1);
-	uint seqno = link->next_out_no;
-	uint bc_last_in = link->owner->bclink.last_in;
+	u16 ack = mod(link->next_in_no - 1);
+	u16 seqno = link->next_out_no;
+	u16 bc_last_in = link->owner->bclink.last_in;
 	struct tipc_media_addr *addr = &link->media_addr;
 	struct sk_buff_head *transmq = &link->transmq;
 	struct sk_buff_head *backlogq = &link->backlogq;
@@ -859,7 +859,7 @@ void tipc_link_push_packets(struct tipc_link *link)
 {
 	struct sk_buff *skb;
 	struct tipc_msg *msg;
-	unsigned int ack = mod(link->next_in_no - 1);
+	u16 ack = mod(link->next_in_no - 1);
 
 	while (skb_queue_len(&link->transmq) < link->window) {
 		skb = __skb_dequeue(&link->backlogq);
@@ -998,13 +998,13 @@ synched:
 static void link_retrieve_defq(struct tipc_link *link,
 			       struct sk_buff_head *list)
 {
-	u32 seq_no;
+	u16 seq_no;
 
 	if (skb_queue_empty(&link->deferdq))
 		return;
 
 	seq_no = buf_seqno(skb_peek(&link->deferdq));
-	if (seq_no == mod(link->next_in_no))
+	if (seq_no == link->next_in_no)
 		skb_queue_splice_tail_init(&link->deferdq, list);
 }
 
@@ -1025,8 +1025,8 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
 	struct tipc_link *l_ptr;
 	struct sk_buff *skb1, *tmp;
 	struct tipc_msg *msg;
-	u32 seq_no;
-	u32 ackd;
+	u16 seq_no;
+	u16 ackd;
 	u32 released;
 
 	skb2list(skb, &head);
@@ -1119,7 +1119,7 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
 		}
 
 		/* Link is now in state WORKING_WORKING */
-		if (unlikely(seq_no != mod(l_ptr->next_in_no))) {
+		if (unlikely(seq_no != l_ptr->next_in_no)) {
 			link_handle_out_of_seq_msg(l_ptr, skb);
 			link_retrieve_defq(l_ptr, &head);
 			skb = NULL;
@@ -1250,7 +1250,7 @@ static void tipc_link_input(struct tipc_link *link, struct sk_buff *skb)
 u32 tipc_link_defer_pkt(struct sk_buff_head *list, struct sk_buff *skb)
 {
 	struct sk_buff *skb1;
-	u32 seq_no = buf_seqno(skb);
+	u16 seq_no = buf_seqno(skb);
 
 	/* Empty queue ? */
 	if (skb_queue_empty(list)) {
@@ -1266,7 +1266,7 @@ u32 tipc_link_defer_pkt(struct sk_buff_head *list, struct sk_buff *skb)
 
 	/* Locate insertion point in queue, then insert; discard if duplicate */
 	skb_queue_walk(list, skb1) {
-		u32 curr_seqno = buf_seqno(skb1);
+		u16 curr_seqno = buf_seqno(skb1);
 
 		if (seq_no == curr_seqno) {
 			kfree_skb(skb);
@@ -1301,7 +1301,7 @@ static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
 	 * Discard packet if a duplicate; otherwise add it to deferred queue
 	 * and notify peer of gap as per protocol specification
 	 */
-	if (less(seq_no, mod(l_ptr->next_in_no))) {
+	if (less(seq_no, l_ptr->next_in_no)) {
 		l_ptr->stats.duplicates++;
 		kfree_skb(buf);
 		return;
@@ -1326,6 +1326,7 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 	struct tipc_msg *msg = l_ptr->pmsg;
 	u32 msg_size = sizeof(l_ptr->proto_msg);
 	int r_flag;
+	u16 last_rcv;
 
 	/* Don't send protocol message during link failover */
 	if (l_ptr->flags & LINK_FAILINGOVER)
@@ -1342,7 +1343,7 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 	msg_set_last_bcast(msg, tipc_bclink_get_last_sent(l_ptr->owner->net));
 
 	if (msg_typ == STATE_MSG) {
-		u32 next_sent = mod(l_ptr->next_out_no);
+		u16 next_sent = l_ptr->next_out_no;
 
 		if (!tipc_link_is_up(l_ptr))
 			return;
@@ -1350,8 +1351,8 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 			next_sent = buf_seqno(skb_peek(&l_ptr->backlogq));
 		msg_set_next_sent(msg, next_sent);
 		if (!skb_queue_empty(&l_ptr->deferdq)) {
-			u32 rec = buf_seqno(skb_peek(&l_ptr->deferdq));
-			gap = mod(rec - mod(l_ptr->next_in_no));
+			last_rcv = buf_seqno(skb_peek(&l_ptr->deferdq));
+			gap = mod(last_rcv - l_ptr->next_in_no);
 		}
 		msg_set_seq_gap(msg, gap);
 		if (gap)
@@ -1485,10 +1486,8 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr,
 		if (link_reset_unknown(l_ptr))
 			break;
 
-		if (less_eq(mod(l_ptr->next_in_no), msg_next_sent(msg))) {
-			rec_gap = mod(msg_next_sent(msg) -
-				      mod(l_ptr->next_in_no));
-		}
+		if (less_eq(l_ptr->next_in_no, msg_next_sent(msg)))
+			rec_gap = mod(msg_next_sent(msg) - l_ptr->next_in_no);
 
 		if (msg_probe(msg))
 			l_ptr->stats.recv_probes++;