cxgb4vf: Implement "Unhandled Interrupts" statistic

Implement "Unhandled Interrupts" statistic so we can detect when the
hardware tells us that it things we have work to do but we don't find
anything ...
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/cxgb4vf/cxgb4vf_main.c

@@ -1790,7 +1790,7 @@ static int sge_qstats_show(struct seq_file *seq, void *v)
 		  (rxq[qs].rspq.netdev
 		   ? rxq[qs].rspq.netdev->name
 		   : "N/A"));
-		R3("u", "RspQNullInts", rspq.unhandled_irqs);
+		R3("u", "RspQNullInts:", rspq.unhandled_irqs);
 		R("RxPackets:", stats.pkts);
 		R("RxCSO:", stats.rx_cso);
 		R("VLANxtract:", stats.vlan_ex);
@@ -1814,14 +1814,16 @@ static int sge_qstats_show(struct seq_file *seq, void *v)
 		const struct sge_rspq *evtq = &adapter->sge.fw_evtq;
 
 		seq_printf(seq, "%-8s %16s\n", "QType:", "FW event queue");
-		/* no real response queue statistics available to display */
+		seq_printf(seq, "%-16s %8u\n", "RspQNullInts:",
+			   evtq->unhandled_irqs);
 		seq_printf(seq, "%-16s %8u\n", "RspQ CIdx:", evtq->cidx);
 		seq_printf(seq, "%-16s %8u\n", "RspQ Gen:", evtq->gen);
 	} else if (r == 1) {
 		const struct sge_rspq *intrq = &adapter->sge.intrq;
 
 		seq_printf(seq, "%-8s %16s\n", "QType:", "Interrupt Queue");
-		/* no real response queue statistics available to display */
+		seq_printf(seq, "%-16s %8u\n", "RspQNullInts:",
+			   intrq->unhandled_irqs);
 		seq_printf(seq, "%-16s %8u\n", "RspQ CIdx:", intrq->cidx);
 		seq_printf(seq, "%-16s %8u\n", "RspQ Gen:", intrq->gen);
 	}

drivers/net/cxgb4vf/sge.c

@@ -1772,6 +1772,9 @@ static int napi_rx_handler(struct napi_struct *napi, int budget)
 	} else
 		intr_params = QINTR_TIMER_IDX(SGE_TIMER_UPD_CIDX);
 
+	if (unlikely(work_done == 0))
+		rspq->unhandled_irqs++;
+
 	t4_write_reg(rspq->adapter,
 		     T4VF_SGE_BASE_ADDR + SGE_VF_GTS,
 		     CIDXINC(work_done) |