netxen: fix netxen_nic_poll() logic

NAPI poll logic now enforces that a poller returns exactly the budget
when it wants to be called again.

If a driver limits TX completion, it has to return budget as well when
the limit is hit, not the number of received packets.

Reported-and-tested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: d75b1ade567f ("net: less interrupt masking in NAPI")
Cc: Manish Chopra <manish.chopra@qlogic.com>
Acked-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/netxen/netxen_nic_main.c

@@ -2388,7 +2388,10 @@ static int netxen_nic_poll(struct napi_struct *napi, int budget)
 
 	work_done = netxen_process_rcv_ring(sds_ring, budget);
 
-	if ((work_done < budget) && tx_complete) {
+	if (!tx_complete)
+		work_done = budget;
+
+	if (work_done < budget) {
 		napi_complete(&sds_ring->napi);
 		if (test_bit(__NX_DEV_UP, &adapter->state))
 			netxen_nic_enable_int(sds_ring);