1 files changed, 38 insertions, 0 deletions

diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 2df29cbdaf5a..9a6cb22d129f 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -576,6 +576,43 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
                           transport->cwnd, transport->ssthresh);
 }
 
+/* Apply Max.Burst limit to the congestion window:
+ * sctpimpguide-05 2.14.2
+ * D) When the time comes for the sender to
+ * transmit new DATA chunks, the protocol parameter Max.Burst MUST
+ * first be applied to limit how many new DATA chunks may be sent.
+ * The limit is applied by adjusting cwnd as follows:
+ *      if ((flightsize+ Max.Burst * MTU) < cwnd)
+ *              cwnd = flightsize + Max.Burst * MTU
+ */
+
+void sctp_transport_burst_limited(struct sctp_transport *t)
+{
+        struct sctp_association *asoc = t->asoc;
+        u32 old_cwnd = t->cwnd;
+        u32 max_burst_bytes;
+
+        if (t->burst_limited)
+                return;
+
+        max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu);
+        if (max_burst_bytes < old_cwnd) {
+                t->cwnd = max_burst_bytes;
+                t->burst_limited = old_cwnd;
+        }
+}
+
+/* Restore the old cwnd congestion window, after the burst had it's
+ * desired effect.
+ */
+void sctp_transport_burst_reset(struct sctp_transport *t)
+{
+        if (t->burst_limited) {
+                t->cwnd = t->burst_limited;
+                t->burst_limited = 0;
+        }
+}
+
 /* What is the next timeout value for this transport? */
 unsigned long sctp_transport_timeout(struct sctp_transport *t)
 {
@@ -598,6 +635,7 @@ void sctp_transport_reset(struct sctp_transport *t)
          * (see Section 6.2.1)
          */
         t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
+        t->burst_limited = 0;
         t->ssthresh = asoc->peer.i.a_rwnd;
         t->last_rto = t->rto = asoc->rto_initial;
         t->rtt = 0;