sctp: use time_before or time_after for comparing jiffies

The functions time_before or time_after are more robust
for comparing jiffies against other values.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/outqueue.c

@@ -428,7 +428,8 @@ void sctp_retransmit_mark(struct sctp_outq *q,
 			 * retransmitting due to T3 timeout.
 			 */
 			if (reason == SCTP_RTXR_T3_RTX &&
-			    (jiffies - chunk->sent_at) < transport->last_rto)
+			    time_before(jiffies, chunk->sent_at +
+						 transport->last_rto))
 				continue;
 
 			/* RFC 2960 6.2.1 Processing a Received SACK

net/sctp/transport.c

@@ -543,8 +543,8 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
 		 * congestion indications more than once every window of
 		 * data (or more loosely more than once every round-trip time).
 		 */
-		if ((jiffies - transport->last_time_ecne_reduced) >
-		    transport->rtt) {
+		if (time_after(jiffies, transport->last_time_ecne_reduced +
+					transport->rtt)) {
 			transport->ssthresh = max(transport->cwnd/2,
 						  4*transport->asoc->pathmtu);
 			transport->cwnd = transport->ssthresh;
@@ -561,7 +561,8 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
 		 * to be done every RTO interval, we do it every hearbeat
 		 * interval.
 		 */
-		if ((jiffies - transport->last_time_used) > transport->rto)
+		if (time_after(jiffies, transport->last_time_used +
+					transport->rto))
 			transport->cwnd = max(transport->cwnd/2,
 						 4*transport->asoc->pathmtu);
 		break;