sctp: Update SWS avaoidance receiver side algorithm

We currently send window update SACKs every time we free up 1 PMTU
worth of data.  That a lot more SACKs then necessary.  Instead, we'll
now send back the actuall window every time we send a sack, and do
window-update SACKs when a fraction of the receive buffer has been
opened.  The fraction is controlled with a sysctl.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 8e755ebff3b8..37e982510bea 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -1383,8 +1383,9 @@ static inline int sctp_peer_needs_update(struct sctp_association *asoc)
         case SCTP_STATE_SHUTDOWN_RECEIVED:
         case SCTP_STATE_SHUTDOWN_SENT:
                 if ((asoc->rwnd > asoc->a_rwnd) &&
-                    ((asoc->rwnd - asoc->a_rwnd) >=
-                     min_t(__u32, (asoc->base.sk->sk_rcvbuf >> 1), asoc->pathmtu)))
+                    ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
+                           (asoc->base.sk->sk_rcvbuf >> sctp_rwnd_upd_shift),
+                           asoc->pathmtu)))
                         return 1;
                 break;
         default: