ip6_gre: Make IP6GRE and IP6GRETAP devices always NETIF_F_LLTX

Recently we made o_seqno atomic_t.  Stop special-casing TUNNEL_SEQ, and
always mark IP6GRE[TAP] devices as NETIF_F_LLTX, since we no longer need
the TX lock (&txq->_xmit_lock).
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/ipv6/ip6_gre.c

@@ -382,11 +382,6 @@ static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
 		goto failed_free;
 
 	ip6gre_tnl_link_config(nt, 1);
-
-	/* Can use a lockless transmit, unless we generate output sequences */
-	if (!(nt->parms.o_flags & TUNNEL_SEQ))
-		dev->features |= NETIF_F_LLTX;
-
 	ip6gre_tunnel_link(ign, nt);
 	return nt;
 
@@ -1445,26 +1440,23 @@ static void ip6gre_tunnel_setup(struct net_device *dev)
 static void ip6gre_tnl_init_features(struct net_device *dev)
 {
 	struct ip6_tnl *nt = netdev_priv(dev);
+	__be16 flags;
 
-	dev->features		|= GRE6_FEATURES;
+	dev->features		|= GRE6_FEATURES | NETIF_F_LLTX;
 	dev->hw_features	|= GRE6_FEATURES;
 
-	if (!(nt->parms.o_flags & TUNNEL_SEQ)) {
-		/* TCP offload with GRE SEQ is not supported, nor
-		 * can we support 2 levels of outer headers requiring
-		 * an update.
+	flags = nt->parms.o_flags;
+
+	/* TCP offload with GRE SEQ is not supported, nor can we support 2
+	 * levels of outer headers requiring an update.
 	 */
-		if (!(nt->parms.o_flags & TUNNEL_CSUM) ||
-		    nt->encap.type == TUNNEL_ENCAP_NONE) {
+	if (flags & TUNNEL_SEQ)
+		return;
+	if (flags & TUNNEL_CSUM && nt->encap.type != TUNNEL_ENCAP_NONE)
+		return;
+
 	dev->features |= NETIF_F_GSO_SOFTWARE;
 	dev->hw_features |= NETIF_F_GSO_SOFTWARE;
-		}
-
-		/* Can use a lockless transmit, unless we generate
-		 * output sequences
-		 */
-		dev->features |= NETIF_F_LLTX;
-	}
 }
 
 static int ip6gre_tunnel_init_common(struct net_device *dev)