[S390] qeth: buffer count imbalance

The used buffers counter is not incremented in case of an error so
the counter can become negative. Increment the used buffers counter
before checking for errors.
Signed-off-by: NJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/net/qeth_core_main.c

@@ -2840,6 +2840,7 @@ static void qeth_flush_buffers(struct qeth_qdio_out_q *queue, int index,
 		queue->card->perf_stats.outbound_do_qdio_time +=
 			qeth_get_micros() -
 			queue->card->perf_stats.outbound_do_qdio_start_time;
+	atomic_add(count, &queue->used_buffers);
 	if (rc) {
 		queue->card->stats.tx_errors += count;
 		/* ignore temporary SIGA errors without busy condition */
@@ -2853,7 +2854,6 @@ static void qeth_flush_buffers(struct qeth_qdio_out_q *queue, int index,
 		qeth_schedule_recovery(queue->card);
 		return;
 	}
-	atomic_add(count, &queue->used_buffers);
 	if (queue->card->options.performance_stats)
 		queue->card->perf_stats.bufs_sent += count;
 }