macsec: inherit lower device's TSO limits when offloading

JIRA: https://issues.redhat.com/browse/RHEL-26055

commit de187a3
Author: Sabrina Dubroca <sd@queasysnail.net>
Date:   Thu Nov 7 00:13:31 2024 +0100

    macsec: inherit lower device's TSO limits when offloading

    If macsec is offloaded, we need to follow the lower device's
    capabilities, like VLAN devices do.

    Leave the limits unchanged when the offload is disabled.

    Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
    Reviewed-by: Simon Horman <horms@kernel.org>
    Link: https://patch.msgid.link/8240c0181e851f169d815f59658a01fb9dfc5073.1730929545.git.sd@queasysnail.net
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Sabrina Dubroca <sdubroca@redhat.com>

Author: Sabrina Dubroca

drivers/net/macsec.c

@@ -2621,6 +2621,17 @@ static void macsec_set_head_tail_room(struct net_device *dev)
 	dev->needed_tailroom = real_dev->needed_tailroom + needed_tailroom;
 }
 
+static void macsec_inherit_tso_max(struct net_device *dev)
+{
+	struct macsec_dev *macsec = macsec_priv(dev);
+
+	/* if macsec is offloaded, we need to follow the lower
+	 * device's capabilities. otherwise, we can ignore them.
+	 */
+	if (macsec_is_offloaded(macsec))
+		netif_inherit_tso_max(dev, macsec->real_dev);
+}
+
 static int macsec_update_offload(struct net_device *dev, enum macsec_offload offload)
 {
 	enum macsec_offload prev_offload;
@@ -2666,6 +2677,8 @@ static int macsec_update_offload(struct net_device *dev, enum macsec_offload off
 	macsec_set_head_tail_room(dev);
 	macsec->insert_tx_tag = macsec_needs_tx_tag(macsec, ops);
 
+	macsec_inherit_tso_max(dev);
+
 	netdev_update_features(dev);
 
 	return ret;
@@ -3537,6 +3550,8 @@ static int macsec_dev_init(struct net_device *dev)
 	if (err)
 		return err;
 
+	macsec_inherit_tso_max(dev);
+
 	dev->hw_features = real_dev->hw_features & MACSEC_OFFLOAD_FEATURES;
 	dev->hw_features |= NETIF_F_GSO_SOFTWARE;
 
@@ -4479,6 +4494,13 @@ static int macsec_notify(struct notifier_block *this, unsigned long event,
 			if (dev->mtu > mtu)
 				dev_set_mtu(dev, mtu);
 		}
+		break;
+	case NETDEV_FEAT_CHANGE:
+		list_for_each_entry(m, &rxd->secys, secys) {
+			macsec_inherit_tso_max(m->secy.netdev);
+			netdev_update_features(m->secy.netdev);
+		}
+		break;
 	}
 
 	return NOTIFY_OK;