bpf: mlx4: Report bpf_prog ID during XDP_QUERY_PROG

Add support to mlx4 to report bpf_prog ID during XDP_QUERY_PROG.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

@@ -2825,11 +2825,25 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	return err;
 }
 
-static bool mlx4_xdp_attached(struct net_device *dev)
+static u32 mlx4_xdp_query(struct net_device *dev)
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
+	struct mlx4_en_dev *mdev = priv->mdev;
+	const struct bpf_prog *xdp_prog;
+	u32 prog_id = 0;
+
+	if (!priv->tx_ring_num[TX_XDP])
+		return prog_id;
+
+	mutex_lock(&mdev->state_lock);
+	xdp_prog = rcu_dereference_protected(
+		priv->rx_ring[0]->xdp_prog,
+		lockdep_is_held(&mdev->state_lock));
+	if (xdp_prog)
+		prog_id = xdp_prog->aux->id;
+	mutex_unlock(&mdev->state_lock);
 
-	return !!priv->tx_ring_num[TX_XDP];
+	return prog_id;
 }
 
 static int mlx4_xdp(struct net_device *dev, struct netdev_xdp *xdp)
@@ -2838,7 +2852,8 @@ static int mlx4_xdp(struct net_device *dev, struct netdev_xdp *xdp)
 	case XDP_SETUP_PROG:
 		return mlx4_xdp_set(dev, xdp->prog);
 	case XDP_QUERY_PROG:
-		xdp->prog_attached = mlx4_xdp_attached(dev);
+		xdp->prog_id = mlx4_xdp_query(dev);
+		xdp->prog_attached = !!xdp->prog_id;
 		return 0;
 	default:
 		return -EINVAL;