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>
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 808ab75..9e3ba4d 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -704,6 +704,7 @@
 /*
  * 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 *);
 
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index a2909da..3a7f90a 100644
--- a/net/rxrpc/call_event.c
+++ b/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;
 
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index ca3811b..7cb34b2 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -146,6 +146,15 @@
 	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);