1 files changed, 35 insertions, 2 deletions

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 215b56951d76..39c3821b7d3d 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -202,6 +202,7 @@ static struct sctp_association *sctp_association_init(struct sctp_association *a
         asoc->a_rwnd = asoc->rwnd;
 
         asoc->rwnd_over = 0;
+        asoc->rwnd_press = 0;
 
         /* Use my own max window until I learn something better.  */
         asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
@@ -1374,6 +1375,17 @@ void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned len)
                 asoc->rwnd += len;
         }
 
+        /* If we had window pressure, start recovering it
+         * once our rwnd had reached the accumulated pressure
+         * threshold.  The idea is to recover slowly, but up
+         * to the initial advertised window.
+         */
+        if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
+                int change = min(asoc->pathmtu, asoc->rwnd_press);
+                asoc->rwnd += change;
+                asoc->rwnd_press -= change;
+        }
+
         SCTP_DEBUG_PRINTK("%s: asoc %p rwnd increased by %d to (%u, %u) "
                           "- %u\n", __func__, asoc, len, asoc->rwnd,
                           asoc->rwnd_over, asoc->a_rwnd);
@@ -1406,17 +1418,38 @@ void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned len)
 /* Decrease asoc's rwnd by len. */
 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned len)
 {
+        int rx_count;
+        int over = 0;
+
         SCTP_ASSERT(asoc->rwnd, "rwnd zero", return);
         SCTP_ASSERT(!asoc->rwnd_over, "rwnd_over not zero", return);
+
+        if (asoc->ep->rcvbuf_policy)
+                rx_count = atomic_read(&asoc->rmem_alloc);
+        else
+                rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
+
+        /* If we've reached or overflowed our receive buffer, announce
+         * a 0 rwnd if rwnd would still be positive.  Store the
+         * the pottential pressure overflow so that the window can be restored
+         * back to original value.
+         */
+        if (rx_count >= asoc->base.sk->sk_rcvbuf)
+                over = 1;
+
         if (asoc->rwnd >= len) {
                 asoc->rwnd -= len;
+                if (over) {
+                        asoc->rwnd_press = asoc->rwnd;
+                        asoc->rwnd = 0;
+                }
         } else {
                 asoc->rwnd_over = len - asoc->rwnd;
                 asoc->rwnd = 0;
         }
-        SCTP_DEBUG_PRINTK("%s: asoc %p rwnd decreased by %d to (%u, %u)\n",
+        SCTP_DEBUG_PRINTK("%s: asoc %p rwnd decreased by %d to (%u, %u, %u)\n",
                           __func__, asoc, len, asoc->rwnd,
-                          asoc->rwnd_over);
+                          asoc->rwnd_over, asoc->rwnd_press);
 }
 
 /* Build the bind address list for the association based on info from the