rxrpc: Only take the rwind and mtu values from latest ACK

Move the out-of-order and duplicate ACK packet check to before the call to
rxrpc_input_ackinfo() so that the receive window size and MTU size are only
checked in the latest ACK packet and don't regress.

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 10 insertions, 9 deletions

diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index af8ce64f4162..04213a65c1ac 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -868,6 +868,16 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
                                   rxrpc_propose_ack_respond_to_ack);
         }
 
+        /* Discard any out-of-order or duplicate ACKs. */
+        if (before_eq(sp->hdr.serial, call->acks_latest)) {
+                _debug("discard ACK %d <= %d",
+                       sp->hdr.serial, call->acks_latest);
+                return;
+        }
+        call->acks_latest_ts = skb->tstamp;
+        call->acks_latest = sp->hdr.serial;
+
+        /* Parse rwind and mtu sizes if provided. */
         ioffset = offset + nr_acks + 3;
         if (skb->len >= ioffset + sizeof(buf.info)) {
                 if (skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
@@ -889,15 +899,6 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
                 return;
         }
 
-        /* Discard any out-of-order or duplicate ACKs. */
-        if (before_eq(sp->hdr.serial, call->acks_latest)) {
-                _debug("discard ACK %d <= %d",
-                       sp->hdr.serial, call->acks_latest);
-                return;
-        }
-        call->acks_latest_ts = skb->tstamp;
-        call->acks_latest = sp->hdr.serial;
-
         if (before(hard_ack, call->tx_hard_ack) ||
             after(hard_ack, call->tx_top))
                 return rxrpc_proto_abort("AKW", call, 0);