igb: XDP extack message on error

Add an extack error message when the RX buffer size is too small
for the frame size.

Fixes: 9cbc948b ("igb: add XDP support")
Suggested-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Sven Auhagen <sven.auhagen@voleatech.de>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -2824,21 +2824,26 @@ static int igb_setup_tc(struct net_device *dev, enum tc_setup_type type,
 	}
 }
 
-static int igb_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
+static int igb_xdp_setup(struct net_device *dev, struct netdev_bpf *bpf)
 {
 	int i, frame_size = dev->mtu + IGB_ETH_PKT_HDR_PAD;
 	struct igb_adapter *adapter = netdev_priv(dev);
+	struct bpf_prog *prog = bpf->prog, *old_prog;
 	bool running = netif_running(dev);
-	struct bpf_prog *old_prog;
 	bool need_reset;
 
 	/* verify igb ring attributes are sufficient for XDP */
 	for (i = 0; i < adapter->num_rx_queues; i++) {
 		struct igb_ring *ring = adapter->rx_ring[i];
 
-		if (frame_size > igb_rx_bufsz(ring))
+		if (frame_size > igb_rx_bufsz(ring)) {
+			NL_SET_ERR_MSG_MOD(bpf->extack,
+					   "The RX buffer size is too small for the frame size");
+			netdev_warn(dev, "XDP RX buffer size %d is too small for the frame size %d\n",
+				    igb_rx_bufsz(ring), frame_size);
 			return -EINVAL;
 		}
+	}
 
 	old_prog = xchg(&adapter->xdp_prog, prog);
 	need_reset = (!!prog != !!old_prog);
@@ -2869,7 +2874,7 @@ static int igb_xdp(struct net_device *dev, struct netdev_bpf *xdp)
 {
 	switch (xdp->command) {
 	case XDP_SETUP_PROG:
-		return igb_xdp_setup(dev, xdp->prog);
+		return igb_xdp_setup(dev, xdp);
 	default:
 		return -EINVAL;
 	}
@@ -6499,7 +6504,9 @@ static int igb_change_mtu(struct net_device *netdev, int new_mtu)
 			struct igb_ring *ring = adapter->rx_ring[i];
 
 			if (max_frame > igb_rx_bufsz(ring)) {
-				netdev_warn(adapter->netdev, "Requested MTU size is not supported with XDP\n");
+				netdev_warn(adapter->netdev,
+					    "Requested MTU size is not supported with XDP. Max frame size is %d\n",
+					    max_frame);
 				return -EINVAL;
 			}
 		}