net/mlx5e: Don't make internal use of errno to denote missing neigh

EAGAIN is treated as a specific case when we consider the attachment
successful but wait for neigh event before offloading the flow.
This can result in unwanted behavior when sub calls on the offloading
path will return EAGAIN and we pass this error up.

Instead of attaching to a specific error code return a  boolean value
from the attach encap operation saying if the encap is valid or not.

Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

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

@@ -295,7 +295,9 @@ int mlx5e_tc_tun_create_header_ipv4(struct mlx5e_priv *priv,
 
 	if (!(nud_state & NUD_VALID)) {
 		neigh_event_send(n, NULL);
-		err = -EAGAIN;
+		/* the encap entry will be made valid on neigh update event
+		 * and not used before that.
+		 */
 		goto out;
 	}
 
@@ -408,7 +410,9 @@ int mlx5e_tc_tun_create_header_ipv6(struct mlx5e_priv *priv,
 
 	if (!(nud_state & NUD_VALID)) {
 		neigh_event_send(n, NULL);
-		err = -EAGAIN;
+		/* the encap entry will be made valid on neigh update event
+		 * and not used before that.
+		 */
 		goto out;
 	}
 

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

@@ -854,7 +854,8 @@ static int mlx5e_attach_encap(struct mlx5e_priv *priv,
 			      struct net_device *mirred_dev,
 			      int out_index,
 			      struct netlink_ext_ack *extack,
-			      struct net_device **encap_dev);
+			      struct net_device **encap_dev,
+			      bool *encap_valid);
 
 static struct mlx5_flow_handle *
 mlx5e_tc_offload_fdb_rules(struct mlx5_eswitch *esw,
@@ -940,7 +941,8 @@ mlx5e_tc_add_fdb_flow(struct mlx5e_priv *priv,
 	struct mlx5_fc *counter = NULL;
 	struct mlx5e_rep_priv *rpriv;
 	struct mlx5e_priv *out_priv;
-	int err = 0, encap_err = 0;
+	bool encap_valid = true;
+	int err = 0;
 	int out_index;
 
 	if (!mlx5_eswitch_prios_supported(esw) && attr->prio != 1) {
@@ -970,11 +972,10 @@ mlx5e_tc_add_fdb_flow(struct mlx5e_priv *priv,
 		out_dev = __dev_get_by_index(dev_net(priv->netdev),
 					     mirred_ifindex);
 		err = mlx5e_attach_encap(priv, flow, out_dev, out_index,
-					 extack, &encap_dev);
-		if (err && err != -EAGAIN)
+					 extack, &encap_dev, &encap_valid);
+		if (err)
 			goto err_attach_encap;
-		if (err == -EAGAIN)
-			encap_err = err;
+
 		out_priv = netdev_priv(encap_dev);
 		rpriv = out_priv->ppriv;
 		attr->dests[out_index].rep = rpriv->rep;
@@ -1002,10 +1003,11 @@ mlx5e_tc_add_fdb_flow(struct mlx5e_priv *priv,
 		attr->counter = counter;
 	}
 
-	/* we get here if (1) there's no error or when
-	 * (2) there's an encap action and we're on -EAGAIN (no valid neigh)
+	/* we get here if one of the following takes place:
+	 * (1) there's no error
+	 * (2) there's an encap action and we don't have valid neigh
 	 */
-	if (encap_err == -EAGAIN) {
+	if (!encap_valid) {
 		/* continue with goto slow path rule instead */
 		struct mlx5_esw_flow_attr slow_attr;
 
@@ -2343,7 +2345,8 @@ static int mlx5e_attach_encap(struct mlx5e_priv *priv,
 			      struct net_device *mirred_dev,
 			      int out_index,
 			      struct netlink_ext_ack *extack,
-			      struct net_device **encap_dev)
+			      struct net_device **encap_dev,
+			      bool *encap_valid)
 {
 	struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
 	struct mlx5_esw_flow_attr *attr = flow->esw_attr;
@@ -2391,7 +2394,7 @@ static int mlx5e_attach_encap(struct mlx5e_priv *priv,
 	else if (family == AF_INET6)
 		err = mlx5e_tc_tun_create_header_ipv6(priv, mirred_dev, e);
 
-	if (err && err != -EAGAIN)
+	if (err)
 		goto out_err;
 
 	hash_add_rcu(esw->offloads.encap_tbl, &e->encap_hlist, hash_key);
@@ -2403,8 +2406,9 @@ static int mlx5e_attach_encap(struct mlx5e_priv *priv,
 	if (e->flags & MLX5_ENCAP_ENTRY_VALID) {
 		attr->dests[out_index].encap_id = e->encap_id;
 		attr->dests[out_index].flags |= MLX5_ESW_DEST_ENCAP_VALID;
+		*encap_valid = true;
 	} else {
-		err = -EAGAIN;
+		*encap_valid = false;
 	}
 
 	return err;