s390/qeth: count TX completion interrupts

While the qdio layer already tracks the number of HW interrupts for a
device, there's value in understanding how many of them have been
raised due to our TX completion logic.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core.h

@@ -483,6 +483,7 @@ struct qeth_out_q_stats {
 	u64 stopped;
 	u64 doorbell;
 	u64 coal_frames;
+	u64 completion_irq;
 	u64 completion_yield;
 	u64 completion_timer;
 

drivers/s390/net/qeth_core_main.c

@@ -1400,8 +1400,10 @@ static void qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
 	int i;
 
 	/* is PCI flag set on buffer? */
-	if (buf->buffer->element[0].sflags & SBAL_SFLAGS0_PCI_REQ)
+	if (buf->buffer->element[0].sflags & SBAL_SFLAGS0_PCI_REQ) {
 		atomic_dec(&queue->set_pci_flags_count);
+		QETH_TXQ_STAT_INC(queue, completion_irq);
+	}
 
 	qeth_tx_complete_buf(buf, error, budget);
 

drivers/s390/net/qeth_ethtool.c

@@ -41,6 +41,7 @@ static const struct qeth_stats txq_stats[] = {
 	QETH_TXQ_STAT("Queue stopped", stopped),
 	QETH_TXQ_STAT("Doorbell", doorbell),
 	QETH_TXQ_STAT("IRQ for frames", coal_frames),
+	QETH_TXQ_STAT("Completion IRQ", completion_irq),
 	QETH_TXQ_STAT("Completion yield", completion_yield),
 	QETH_TXQ_STAT("Completion timer", completion_timer),
 };