[RFC 4/4] virtio_net: make use of extended ack message reporting

[Jakub Kicinski]

Try to carry error messages to the user via the netlink extended
ack message attribute.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 drivers/net/virtio_net.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 666ada6130ab..96c5bb31f0af 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1788,7 +1788,8 @@ static int virtnet_reset(struct virtnet_info *vi, int 
curr_qp, int xdp_qp)
        return ret;
 }
 
-static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
+static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
+                          struct netlink_ext_ack *extack)
 {
        unsigned long int max_sz = PAGE_SIZE - sizeof(struct padded_vnet_hdr);
        struct virtnet_info *vi = netdev_priv(dev);
@@ -1800,16 +1801,17 @@ static int virtnet_xdp_set(struct net_device *dev, 
struct bpf_prog *prog)
            virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
            virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
            virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO)) {
-               netdev_warn(dev, "can't set XDP while host is implementing LRO, 
disable LRO first\n");
+               NL_SET_ERR_MSG(extack, "can't set XDP while host is 
implementing LRO, disable LRO first");
                return -EOPNOTSUPP;
        }
 
        if (vi->mergeable_rx_bufs && !vi->any_header_sg) {
-               netdev_warn(dev, "XDP expects header/data in single page, 
any_header_sg required\n");
+               NL_SET_ERR_MSG(extack, "XDP expects header/data in single page, 
any_header_sg required");
                return -EINVAL;
        }
 
        if (dev->mtu > max_sz) {
+               NL_SET_ERR_MSG(extack, "MTU too large to enable XDP");
                netdev_warn(dev, "XDP requires MTU less than %lu\n", max_sz);
                return -EINVAL;
        }
@@ -1820,6 +1822,7 @@ static int virtnet_xdp_set(struct net_device *dev, struct 
bpf_prog *prog)
 
        /* XDP requires extra queues for XDP_TX */
        if (curr_qp + xdp_qp > vi->max_queue_pairs) {
+               NL_SET_ERR_MSG(extack, "Too few free TX rings available");
                netdev_warn(dev, "request %i queues but max is %i\n",
                            curr_qp + xdp_qp, vi->max_queue_pairs);
                return -ENOMEM;
@@ -1881,7 +1884,7 @@ static int virtnet_xdp(struct net_device *dev, struct 
netdev_xdp *xdp)
 {
        switch (xdp->command) {
        case XDP_SETUP_PROG:
-               return virtnet_xdp_set(dev, xdp->prog);
+               return virtnet_xdp_set(dev, xdp->prog, xdp->extack);
        case XDP_QUERY_PROG:
                xdp->prog_attached = virtnet_xdp_query(dev);
                return 0;
-- 
2.11.0