mlx5: Don't accidentally set RTO_ONLINK before mlx5e_route_lookup_ipv4_get()

Mask the ECN bits before calling mlx5e_route_lookup_ipv4_get(). The
tunnel key might have the last ECN bit set. This interferes with the
route lookup process as ip_route_output_key_hash() interpretes this bit
specially (to restrict the route scope).

Found by code inspection, compile tested only.

Fixes: c7b9038d ("net/mlx5e: TC preparation refactoring for routing update event")
Fixes: 9a941117 ("net/mlx5e: Maximize ip tunnel key usage on the TC offloading path")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c

 /* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
 /* Copyright (c) 2018 Mellanox Technologies. */
 
+#include <net/inet_ecn.h>
 #include <net/vxlan.h>
 #include <net/gre.h>
 #include <net/geneve.h>
@@ -235,7 +236,7 @@ int mlx5e_tc_tun_create_header_ipv4(struct mlx5e_priv *priv,
 	int err;
 
 	/* add the IP fields */
-	attr.fl.fl4.flowi4_tos = tun_key->tos;
+	attr.fl.fl4.flowi4_tos = tun_key->tos & ~INET_ECN_MASK;
 	attr.fl.fl4.daddr = tun_key->u.ipv4.dst;
 	attr.fl.fl4.saddr = tun_key->u.ipv4.src;
 	attr.ttl = tun_key->ttl;
@@ -350,7 +351,7 @@ int mlx5e_tc_tun_update_header_ipv4(struct mlx5e_priv *priv,
 	int err;
 
 	/* add the IP fields */
-	attr.fl.fl4.flowi4_tos = tun_key->tos;
+	attr.fl.fl4.flowi4_tos = tun_key->tos & ~INET_ECN_MASK;
 	attr.fl.fl4.daddr = tun_key->u.ipv4.dst;
 	attr.fl.fl4.saddr = tun_key->u.ipv4.src;
 	attr.ttl = tun_key->ttl;