From: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Date: Tue, 20 Jun 2017 16:00:32 +0200
Subject: s390/qeth: fix packing buffer statistics
Patch-mainline: v4.13-rc1
Git-commit: 3cdc8a25297e4e0646c3e72671c95f065117a9fd
References: bsc#1061024 FATE#323301

There's two spots in qeth_send_packet() where we don't accurately
account for transmitted packing buffers in qeth's performance
statistics:

1) when flushing the current buffer due to insufficient size,
   and the next buffer is not EMPTY, we need to account for that
   flushed buffer.
2) when synchronizing with the TX completion code, we reset
   flush_count and thus forget to account for any previously
   flushed buffers.

Reported-by: Nils Hoppmann <niho@de.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/s390/net/qeth_core_main.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -4103,7 +4103,8 @@ int qeth_do_send_packet(struct qeth_card
 							   flush_count);
 				atomic_set(&queue->state,
 						QETH_OUT_Q_UNLOCKED);
-				return -EBUSY;
+				rc = -EBUSY;
+				goto out;
 			}
 		}
 	}
@@ -4122,19 +4123,21 @@ int qeth_do_send_packet(struct qeth_card
 	 * In that case we will enter this loop
 	 */
 	while (atomic_dec_return(&queue->state)) {
-		flush_count = 0;
 		start_index = queue->next_buf_to_fill;
 		/* check if we can go back to non-packing state */
-		flush_count += qeth_switch_to_nonpacking_if_needed(queue);
+		tmp = qeth_switch_to_nonpacking_if_needed(queue);
 		/*
 		 * check if we need to flush a packing buffer to get a pci
 		 * flag out on the queue
 		 */
-		if (!flush_count && !atomic_read(&queue->set_pci_flags_count))
-			flush_count += qeth_prep_flush_pack_buffer(queue);
-		if (flush_count)
-			qeth_flush_buffers(queue, start_index, flush_count);
+		if (!tmp && !atomic_read(&queue->set_pci_flags_count))
+			tmp = qeth_prep_flush_pack_buffer(queue);
+		if (tmp) {
+			qeth_flush_buffers(queue, start_index, tmp);
+			flush_count += tmp;
+		}
 	}
+out:
 	/* at this point the queue is UNLOCKED again */
 	if (queue->card->options.performance_stats && do_pack)
 		queue->card->perf_stats.bufs_sent_pack += flush_count;