s390/qeth: Reset address notification in case of buffer overflow

In case hardware sends more device-to-bridge-address-change notfications
than the qeth-l2 driver can handle, the hardware will send an overflow
event and then stop sending any events. It expects software to flush its
FDB and start over again. Re-enabling address-change-notification will
report all current addresses.

In order to re-enable address-change-notification this patch defines
the functions qeth_l2_dev2br_an_set() and qeth_l2_dev2br_an_set_cb
to enable or disable dev-to-bridge-address-notification.

A following patch will use the learning_sync bridgeport flag to trigger
enabling or disabling of address-change-notification, so we define
priv->brport_features to store the current setting. BRIDGE_INFO and
ADDR_INFO functionality are mutually exclusive, whereas ADDR_INFO and
qeth_l2_vnicc* can be used together.

Alternative implementations to handle buffer overflow:
Just re-enabling notification and adding all newly reported addresses
would cover any lost 'add' events, but not the lost 'delete' events.
Then these invalid addresses would stay in the bridge FDB as long as the
device exists.
Setting the net device down and up, would be an alternative, but is a bit
drastic. If the net device has many secondary addresses this will create
many delete/add events at its peers which could de-stabilize the
network segment.

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

1 files changed, 8 insertions, 8 deletions

diff --git a/drivers/s390/net/qeth_l2_sys.c b/drivers/s390/net/qeth_l2_sys.c
index 4695d25e54f2..4ba3bc57263f 100644
--- a/drivers/s390/net/qeth_l2_sys.c
+++ b/drivers/s390/net/qeth_l2_sys.c
@@ -18,7 +18,7 @@ static ssize_t qeth_bridge_port_role_state_show(struct device *dev,
 	int rc = 0;
 	char *word;
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		return sprintf(buf, "n/a (VNIC characteristics)\n");
 
 	mutex_lock(&card->sbp_lock);
@@ -65,7 +65,7 @@ static ssize_t qeth_bridge_port_role_show(struct device *dev,
 {
 	struct qeth_card *card = dev_get_drvdata(dev);
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		return sprintf(buf, "n/a (VNIC characteristics)\n");
 
 	return qeth_bridge_port_role_state_show(dev, attr, buf, 0);
@@ -90,7 +90,7 @@ static ssize_t qeth_bridge_port_role_store(struct device *dev,
 	mutex_lock(&card->conf_mutex);
 	mutex_lock(&card->sbp_lock);
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		rc = -EBUSY;
 	else if (card->options.sbp.reflect_promisc)
 		/* Forbid direct manipulation */
@@ -116,7 +116,7 @@ static ssize_t qeth_bridge_port_state_show(struct device *dev,
 {
 	struct qeth_card *card = dev_get_drvdata(dev);
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		return sprintf(buf, "n/a (VNIC characteristics)\n");
 
 	return qeth_bridge_port_role_state_show(dev, attr, buf, 1);
@@ -131,7 +131,7 @@ static ssize_t qeth_bridgeport_hostnotification_show(struct device *dev,
 	struct qeth_card *card = dev_get_drvdata(dev);
 	int enabled;
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		return sprintf(buf, "n/a (VNIC characteristics)\n");
 
 	enabled = card->options.sbp.hostnotification;
@@ -153,7 +153,7 @@ static ssize_t qeth_bridgeport_hostnotification_store(struct device *dev,
 	mutex_lock(&card->conf_mutex);
 	mutex_lock(&card->sbp_lock);
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		rc = -EBUSY;
 	else if (qeth_card_hw_is_reachable(card)) {
 		rc = qeth_bridgeport_an_set(card, enable);
@@ -179,7 +179,7 @@ static ssize_t qeth_bridgeport_reflect_show(struct device *dev,
 	struct qeth_card *card = dev_get_drvdata(dev);
 	char *state;
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		return sprintf(buf, "n/a (VNIC characteristics)\n");
 
 	if (card->options.sbp.reflect_promisc) {
@@ -215,7 +215,7 @@ static ssize_t qeth_bridgeport_reflect_store(struct device *dev,
 	mutex_lock(&card->conf_mutex);
 	mutex_lock(&card->sbp_lock);
 
-	if (qeth_l2_vnicc_is_in_use(card))
+	if (!qeth_bridgeport_allowed(card))
 		rc = -EBUSY;
 	else if (card->options.sbp.role != QETH_SBP_ROLE_NONE)
 		rc = -EPERM;