From: Julian Wiedmann <jwi@linux.ibm.com>
Subject: s390/qeth: use DEFINE_MUTEX for qeth_mod_mutex
Patch-mainline: v4.20-rc1
Git-commit: a70fee3b0f9007ee16bf0159018ee29684acfac0
References: FATE#326377, LTC#169210, bsc#1115382

Summary:        qeth: Full-blown TCP Segmentation Offload
Description:    As of now, qeth only supports TCP Segmentation Offload (TSO)
                for IPv4 in Layer3 devices. This feature extends the existing
                support to IPv6, and adds support for TSO in both IP variants
                for Layer2.

                To cleanly pull in all the necessary changes to the transmit
                code, update the qeth driver to the current 4.20 level.


Upstream-Description:

             s390/qeth: use DEFINE_MUTEX for qeth_mod_mutex

             Consolidate declaration and initialization of a static variable.
             While at it reduce its scope in qeth_core_load_discipline(), and simplify
             the return logic accordingly.

             Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
             Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/net/qeth_core_main.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -61,7 +61,6 @@ static struct kmem_cache *qeth_qdio_outb
 
 static struct device *qeth_core_root_dev;
 static struct lock_class_key qdio_out_skb_queue_key;
-static struct mutex qeth_mod_mutex;
 
 static void qeth_send_control_data_cb(struct qeth_channel *,
 			struct qeth_cmd_buffer *);
@@ -5585,11 +5584,11 @@ static int qeth_register_dbf_views(void)
 	return 0;
 }
 
+static DEFINE_MUTEX(qeth_mod_mutex);	/* for synchronized module loading */
+
 int qeth_core_load_discipline(struct qeth_card *card,
 		enum qeth_discipline_id discipline)
 {
-	int rc = 0;
-
 	mutex_lock(&qeth_mod_mutex);
 	switch (discipline) {
 	case QETH_DISCIPLINE_LAYER3:
@@ -5603,14 +5602,15 @@ int qeth_core_load_discipline(struct qet
 	default:
 		break;
 	}
+	mutex_unlock(&qeth_mod_mutex);
 
 	if (!card->discipline) {
 		dev_err(&card->gdev->dev, "There is no kernel module to "
 			"support discipline %d\n", discipline);
-		rc = -EINVAL;
+		return -EINVAL;
 	}
-	mutex_unlock(&qeth_mod_mutex);
-	return rc;
+
+	return 0;
 }
 
 void qeth_core_free_discipline(struct qeth_card *card)
@@ -6619,7 +6619,6 @@ static int __init qeth_core_init(void)
 	INIT_LIST_HEAD(&qeth_core_card_list.list);
 	INIT_LIST_HEAD(&qeth_dbf_list);
 	rwlock_init(&qeth_core_card_list.rwlock);
-	mutex_init(&qeth_mod_mutex);
 
 	qeth_wq = create_singlethread_workqueue("qeth_wq");
 	if (!qeth_wq) {