rxrpc: Need to start the resend timer on initial transmission

When a DATA packet has its initial transmission, we may need to start or
adjust the resend timer.  Without this we end up relying on being sent a
NACK to initiate the resend.
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/ar-internal.h

@@ -704,6 +704,7 @@ int rxrpc_reject_call(struct rxrpc_sock *);
 /*
  * call_event.c
  */
+void rxrpc_set_timer(struct rxrpc_call *);
 void rxrpc_propose_ACK(struct rxrpc_call *, u8, u16, u32, bool, bool);
 void rxrpc_process_call(struct work_struct *);
 

net/rxrpc/call_event.c

@@ -24,7 +24,7 @@
 /*
  * Set the timer
  */
-static void rxrpc_set_timer(struct rxrpc_call *call)
+void rxrpc_set_timer(struct rxrpc_call *call)
 {
 	unsigned long t, now = jiffies;
 

net/rxrpc/sendmsg.c

@@ -146,6 +146,15 @@ static void rxrpc_queue_packet(struct rxrpc_call *call, struct sk_buff *skb,
 	if (ret < 0) {
 		_debug("need instant resend %d", ret);
 		rxrpc_instant_resend(call, ix);
+	} else {
+		unsigned long resend_at;
+
+		resend_at = jiffies + msecs_to_jiffies(rxrpc_resend_timeout);
+
+		if (time_before(resend_at, call->resend_at)) {
+			call->resend_at = resend_at;
+			rxrpc_set_timer(call);
+		}
 	}
 
 	rxrpc_free_skb(skb, rxrpc_skb_tx_freed);