rxrpc: Only ping for lost reply in client call

When a reply is deemed lost, we send a ping to find out the other end
received all the request data packets we sent.  This should be limited to
client calls and we shouldn't do this on service calls.
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/input.c

@@ -847,7 +847,8 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
 
 	if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 	    RXRPC_TX_ANNO_LAST &&
-	    summary.nr_acks == call->tx_top - hard_ack)
+	    summary.nr_acks == call->tx_top - hard_ack &&
+	    rxrpc_is_client_call(call))
 		rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 				  false, true,
 				  rxrpc_propose_ack_ping_for_lost_reply);