From: Stephen Hemminger <stephen@networkplumber.org>

Give a reason for returning error for bpf setup.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 25 +++++++++++++--
----
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index a4e7584a50cb..9a81123074ca 100644

--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -10224,18 +10224,23 @@ ixgbe_features_check(struct sk_buff *skb,

struct net_device *dev,
 	return features;
 }
 
-static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog
*prog)
+static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog
*prog,
+			   struct netlink_ext_ack *extack)
 {
 	int i, frame_size = dev->mtu + ETH_HLEN + ETH_FCS_LEN +
VLAN_HLEN;
 	struct ixgbe_adapter *adapter = netdev_priv(dev);
 	struct bpf_prog *old_prog;
 	bool need_reset;
 
-	if (adapter->flags & IXGBE_FLAG_SRIOV_ENABLED)
+	if (adapter->flags & IXGBE_FLAG_SRIOV_ENABLED) {
+		NL_SET_ERR_MSG(extack, "XDP not support with SRIOV
enabled");

 		return -EINVAL;
+	}
 
-	if (adapter->flags & IXGBE_FLAG_DCB_ENABLED)
+	if (adapter->flags & IXGBE_FLAG_DCB_ENABLED) {
+		NL_SET_ERR_MSG(extack, "XDP not supported with DCB
enabled");
 		return -EINVAL;
+	}
 
 	/* verify ixgbe ring attributes are sufficient for XDP */
 	for (i = 0; i < adapter->num_rx_queues; i++) {

@@ -10244,12 +10249,17 @@ static int ixgbe_xdp_setup(struct

net_device *dev, struct bpf_prog *prog)
 		if (ring_is_rsc_enabled(ring))
 			return -EINVAL;
 
-		if (frame_size > ixgbe_rx_bufsz(ring))
+		if (frame_size > ixgbe_rx_bufsz(ring)) {
+			NL_SET_ERR_MSG(extack,
+				       "XDP does not support multiple
buffers");
 			return -EINVAL;
+		}
 	}
 
-	if (nr_cpu_ids > MAX_XDP_QUEUES)
+	if (nr_cpu_ids > MAX_XDP_QUEUES) {
+		NL_SET_ERR_MSG(extack, "number of cpus >
MAX_XDP_QUEUES");
 		return -ENOMEM;
+	}
 
 	old_prog = xchg(&adapter->xdp_prog, prog);
 	need_reset = (!!prog != !!old_prog);

@@ -10260,7 +10270,7 @@ static int ixgbe_xdp_setup(struct net_device

*dev, struct bpf_prog *prog)
 
 		if (err) {
 			rcu_assign_pointer(adapter->xdp_prog,
old_prog);
-			return -EINVAL;
+			return err;
 		}
 	} else {
 		for (i = 0; i < adapter->num_rx_queues; i++)

@@ -10288,7 +10298,7 @@ static int ixgbe_xdp(struct net_device *dev,

struct netdev_bpf *xdp)
 
 	switch (xdp->command) {
 	case XDP_SETUP_PROG:
-		return ixgbe_xdp_setup(dev, xdp->prog);
+		return ixgbe_xdp_setup(dev, xdp->prog, xdp->extack);
 	case XDP_QUERY_PROG:
 		xdp->prog_id = adapter->xdp_prog ?
 			adapter->xdp_prog->aux->id : 0;

@@ -10298,6 +10308,7 @@ static int ixgbe_xdp(struct net_device *dev,

struct netdev_bpf *xdp)
 					    xdp->xsk.queue_id);
 
 	default:
+		NL_SET_ERR_MSG(xdp->extack, "Unknown XDP command");
 		return -EINVAL;
 	}
 }