net/mlx5e: Protect tc flow table with mutex

TC flow table is created when first flow is added, and destroyed when last
flow is removed. This assumes that all accesses to the table are externally
synchronized with rtnl lock. To remove dependency on rtnl lock, add new
mutex mlx5e_tc_table->t_lock and use it to protect the flow table.
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Jianbo Liu <jianbol@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en/fs.h

@@ -10,6 +10,8 @@ enum {
 };
 
 struct mlx5e_tc_table {
+	/* protects flow table */
+	struct mutex			t_lock;
 	struct mlx5_flow_table		*t;
 
 	struct rhashtable               ht;

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

@@ -854,6 +854,7 @@ mlx5e_tc_add_nic_flow(struct mlx5e_priv *priv,
 			return err;
 	}
 
+	mutex_lock(&priv->fs.tc.t_lock);
 	if (IS_ERR_OR_NULL(priv->fs.tc.t)) {
 		int tc_grp_size, tc_tbl_size;
 		u32 max_flow_counter;
@@ -873,6 +874,7 @@ mlx5e_tc_add_nic_flow(struct mlx5e_priv *priv,
 							    MLX5E_TC_TABLE_NUM_GROUPS,
 							    MLX5E_TC_FT_LEVEL, 0);
 		if (IS_ERR(priv->fs.tc.t)) {
+			mutex_unlock(&priv->fs.tc.t_lock);
 			NL_SET_ERR_MSG_MOD(extack,
 					   "Failed to create tc offload table\n");
 			netdev_err(priv->netdev,
@@ -886,6 +888,7 @@ mlx5e_tc_add_nic_flow(struct mlx5e_priv *priv,
 
 	flow->rule[0] = mlx5_add_flow_rules(priv->fs.tc.t, &parse_attr->spec,
 					    &flow_act, dest, dest_ix);
+	mutex_unlock(&priv->fs.tc.t_lock);
 
 	if (IS_ERR(flow->rule[0]))
 		return PTR_ERR(flow->rule[0]);
@@ -904,10 +907,12 @@ static void mlx5e_tc_del_nic_flow(struct mlx5e_priv *priv,
 		mlx5_del_flow_rules(flow->rule[0]);
 	mlx5_fc_destroy(priv->mdev, counter);
 
+	mutex_lock(&priv->fs.tc.t_lock);
 	if (!mlx5e_tc_num_filters(priv, MLX5_TC_FLAG(NIC_OFFLOAD)) && priv->fs.tc.t) {
 		mlx5_destroy_flow_table(priv->fs.tc.t);
 		priv->fs.tc.t = NULL;
 	}
+	mutex_unlock(&priv->fs.tc.t_lock);
 
 	if (attr->action & MLX5_FLOW_CONTEXT_ACTION_MOD_HDR)
 		mlx5e_detach_mod_hdr(priv, flow);
@@ -3684,6 +3689,7 @@ int mlx5e_tc_nic_init(struct mlx5e_priv *priv)
 	struct mlx5e_tc_table *tc = &priv->fs.tc;
 	int err;
 
+	mutex_init(&tc->t_lock);
 	hash_init(tc->mod_hdr_tbl);
 	hash_init(tc->hairpin_tbl);
 
@@ -3722,6 +3728,7 @@ void mlx5e_tc_nic_cleanup(struct mlx5e_priv *priv)
 		mlx5_destroy_flow_table(tc->t);
 		tc->t = NULL;
 	}
+	mutex_destroy(&tc->t_lock);
 }
 
 int mlx5e_tc_esw_init(struct rhashtable *tc_ht)