Subject: [PATCH 32/53] s390/qeth: lock read device while queueing next buffer

From: Julian Wiedmann <[email-masked]>
Date: Tue, 20 Mar 2018 07:59:14 +0100

[ Upstream commit 17bf8c9b3d499d5168537c98b61eb7a1fcbca6c2 ]

For calling ccw_device_start(), issue_next_read() needs to hold the
device's ccwlock.
This is satisfied for the IRQ handler path (where qeth_irq() gets called
under the ccwlock), but we need explicit locking for the initial call by
the MPC initialization.

Signed-off-by: Julian Wiedmann <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/s390/net/qeth_core_main.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index d91a52dacaf5..aec8ba8b9e35 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -526,8 +526,7 @@ static inline int qeth_is_cq(struct qeth_card *card, unsigned int queue)
 	    queue == card->qdio.no_in_queues - 1;
 }
 
-
-static int qeth_issue_next_read(struct qeth_card *card)
+static int __qeth_issue_next_read(struct qeth_card *card)
 {
 	int rc;
 	struct qeth_cmd_buffer *iob;
@@ -558,6 +557,17 @@ static int qeth_issue_next_read(struct qeth_card *card)
 	return rc;
 }
 
+static int qeth_issue_next_read(struct qeth_card *card)
+{
+	int ret;
+
+	spin_lock_irq(get_ccwdev_lock(CARD_RDEV(card)));
+	ret = __qeth_issue_next_read(card);
+	spin_unlock_irq(get_ccwdev_lock(CARD_RDEV(card)));
+
+	return ret;
+}
+
 static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card)
 {
 	struct qeth_reply *reply;
@@ -1183,7 +1193,7 @@ static void qeth_irq(struct ccw_device *cdev, unsigned long intparm,
 		return;
 	if (channel == &card->read &&
 	    channel->state == CH_STATE_UP)
-		qeth_issue_next_read(card);
+		__qeth_issue_next_read(card);
 
 	iob = channel->iob;
 	index = channel->buf_no;
-- 
2.14.3