[PATCH 4.4 16/20] s390/qeth: lock read device while queueing next buffer

Greg Kroah-Hartman
2018-03-29T18:00:52Z

From: Julian Wiedmann <jwi@linux.vnet.ibm.com>

[ 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 <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/s390/net/qeth_core_main.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -517,8 +517,7 @@ static inline int qeth_is_cq(struct qeth
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;
@@ -549,6 +548,17 @@ static int qeth_issue_next_read(struct q
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;
@@ -1174,7 +1184,7 @@ static void qeth_irq(struct ccw_device *
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;