qeth: restore device features after recovery

After device recovery, only a basic set of network device features is
enabled on the device. If features like checksum offloading or TSO were
enabled by the user before the recovery, this results in a mismatch
between the network device features, that the kernel assumes to be
enabled on the device, and the features actually enabled on the device.

This patch tries to restore previously set features, that require
changes on the device, after the recovery of a device. In case of an
error, the network device's features are changed to contain only the
features that are actually turned on.

Signed-off-by: Hans Wippel <hwippel@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core.h

@@ -999,6 +999,7 @@ struct qeth_cmd_buffer *qeth_get_setassparms_cmd(struct qeth_card *,
 						 __u16, __u16,
 						 enum qeth_prot_versions);
 int qeth_set_features(struct net_device *, netdev_features_t);
+int qeth_recover_features(struct net_device *);
 netdev_features_t qeth_fix_features(struct net_device *, netdev_features_t);
 
 /* exports for OSN */

drivers/s390/net/qeth_core_main.c

@@ -6131,6 +6131,35 @@ static int qeth_set_ipa_tso(struct qeth_card *card, int on)
 	return rc;
 }
 
+/* try to restore device features on a device after recovery */
+int qeth_recover_features(struct net_device *dev)
+{
+	struct qeth_card *card = dev->ml_priv;
+	netdev_features_t recover = dev->features;
+
+	if (recover & NETIF_F_IP_CSUM) {
+		if (qeth_set_ipa_csum(card, 1, IPA_OUTBOUND_CHECKSUM))
+			recover ^= NETIF_F_IP_CSUM;
+	}
+	if (recover & NETIF_F_RXCSUM) {
+		if (qeth_set_ipa_csum(card, 1, IPA_INBOUND_CHECKSUM))
+			recover ^= NETIF_F_RXCSUM;
+	}
+	if (recover & NETIF_F_TSO) {
+		if (qeth_set_ipa_tso(card, 1))
+			recover ^= NETIF_F_TSO;
+	}
+
+	if (recover == dev->features)
+		return 0;
+
+	dev_warn(&card->gdev->dev,
+		 "Device recovery failed to restore all offload features\n");
+	dev->features = recover;
+	return -EIO;
+}
+EXPORT_SYMBOL_GPL(qeth_recover_features);
+
 int qeth_set_features(struct net_device *dev, netdev_features_t features)
 {
 	struct qeth_card *card = dev->ml_priv;

drivers/s390/net/qeth_l2_main.c

@@ -1246,6 +1246,9 @@ contin:
 		}
 		/* this also sets saved unicast addresses */
 		qeth_l2_set_rx_mode(card->dev);
+		rtnl_lock();
+		qeth_recover_features(card->dev);
+		rtnl_unlock();
 	}
 	/* let user_space know that device is online */
 	kobject_uevent(&gdev->dev.kobj, KOBJ_CHANGE);

drivers/s390/net/qeth_l3_main.c

@@ -3269,6 +3269,7 @@ contin:
 		else
 			dev_open(card->dev);
 		qeth_l3_set_multicast_list(card->dev);
+		qeth_recover_features(card->dev);
 		rtnl_unlock();
 	}
 	qeth_trace_features(card);