net/mlx5e: Only access fully initialized flows in neigh update

To remove dependency on rtnl lock and prevent neigh update code from
accessing uninitialized flows when executing concurrently with tc, extend
mlx5e_tc_flow with 'init_done' completion. Modify helper
mlx5e_take_all_encap_flows() to wait for flow completion after obtaining
reference to it. Modify mlx5e_tc_encap_flows_del() and
mlx5e_tc_encap_flows_add() to skip flows that don't have OFFLOADED flag
set, which can happen if concurrent flow initialization failed.

This commit finishes neigh update refactoring for concurrent execution
started in previous change in this series.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c

@@ -130,6 +130,7 @@ struct mlx5e_tc_flow {
 	struct list_head	tmp_list; /* temporary flow list used by neigh update */
 	refcount_t		refcnt;
 	struct rcu_head		rcu_head;
+	struct completion	init_done;
 	union {
 		struct mlx5_esw_flow_attr esw_attr[0];
 		struct mlx5_nic_flow_attr nic_attr[0];
@@ -1319,6 +1320,8 @@ void mlx5e_tc_encap_flows_add(struct mlx5e_priv *priv,
 		bool all_flow_encaps_valid = true;
 		int i;
 
+		if (!mlx5e_is_offloaded_flow(flow))
+			continue;
 		esw_attr = flow->esw_attr;
 		spec = &esw_attr->parse_attr->spec;
 
@@ -1367,6 +1370,8 @@ void mlx5e_tc_encap_flows_del(struct mlx5e_priv *priv,
 	int err;
 
 	list_for_each_entry(flow, flow_list, tmp_list) {
+		if (!mlx5e_is_offloaded_flow(flow))
+			continue;
 		spec = &flow->esw_attr->parse_attr->spec;
 
 		/* update from encap rule to slow path rule */
@@ -1412,6 +1417,7 @@ void mlx5e_take_all_encap_flows(struct mlx5e_encap_entry *e, struct list_head *f
 		flow = container_of(efi, struct mlx5e_tc_flow, encaps[efi->index]);
 		if (IS_ERR(mlx5e_flow_get(flow)))
 			continue;
+		wait_for_completion(&flow->init_done);
 
 		flow->tmp_efi_index = efi->index;
 		list_add(&flow->tmp_list, flow_list);
@@ -3492,6 +3498,7 @@ mlx5e_alloc_flow(struct mlx5e_priv *priv, int attr_size,
 	INIT_LIST_HEAD(&flow->mod_hdr);
 	INIT_LIST_HEAD(&flow->hairpin);
 	refcount_set(&flow->refcnt, 1);
+	init_completion(&flow->init_done);
 
 	*__flow = flow;
 	*__parse_attr = parse_attr;
@@ -3564,6 +3571,7 @@ __mlx5e_add_fdb_flow(struct mlx5e_priv *priv,
 		goto err_free;
 
 	err = mlx5e_tc_add_fdb_flow(priv, flow, extack);
+	complete_all(&flow->init_done);
 	if (err) {
 		if (!(err == -ENETUNREACH && mlx5_lag_is_multipath(in_mdev)))
 			goto err_free;