qeth: avoid crash in case of layer mismatch for VSWITCH

For z/VM GuestLAN or VSWITCH devices the transport layer is
configured in z/VM. The layer2 attribute of a participating Linux
device has to match the z/VM definition. In case of a mismatch
Linux currently crashes in qeth recovery due to a reference to the
not yet existing net_device.
Solution: add a check for existence of net_device and add a message
pointing to the mismatch of layer definitions in Linux and z/VM.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 14 insertions, 6 deletions

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 89867bc43f7a..ffe6960cb30a 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -572,6 +572,10 @@ static void qeth_send_control_data_cb(struct qeth_channel *channel,
         card = CARD_FROM_CDEV(channel->ccwdev);
         if (qeth_check_idx_response(iob->data)) {
                 qeth_clear_ipacmd_list(card);
+                if (((iob->data[2] & 0xc0) == 0xc0) && iob->data[4] == 0xf6)
+                        dev_err(&card->gdev->dev,
+                                "The qeth device is not configured "
+                                "for the OSI layer required by z/VM\n");
                 qeth_schedule_recovery(card);
                 goto out;
         }
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 2c48591ced44..21627ba3093b 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -1126,9 +1126,11 @@ static int qeth_l2_recover(void *ptr)
                 dev_info(&card->gdev->dev,
                         "Device successfully recovered!\n");
         else {
-                rtnl_lock();
-                dev_close(card->dev);
-                rtnl_unlock();
+                if (card->dev) {
+                        rtnl_lock();
+                        dev_close(card->dev);
+                        rtnl_unlock();
+                }
                 dev_warn(&card->gdev->dev, "The qeth device driver "
                         "failed to recover an error on the device\n");
         }
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index cdd6ab9c894d..8f30085ef5b4 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2082,9 +2082,11 @@ static int qeth_l3_stop_card(struct qeth_card *card, int recovery_mode)
                 if (recovery_mode)
                         qeth_l3_stop(card->dev);
                 else {
-                        rtnl_lock();
-                        dev_close(card->dev);
-                        rtnl_unlock();
+                        if (card->dev) {
+                                rtnl_lock();
+                                dev_close(card->dev);
+                                rtnl_unlock();
+                        }
                 }
                 if (!card->use_hard_stop) {
                         rc = qeth_send_stoplan(card);