From: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx> Date: Wed, 12 Apr 2017 13:54:20 -0600 > packet passed to xdp seems to be messed up Ok, the problem is that skb->mac_len isn't set properly at this point. That doesn't happen until __netif_receive_skb_core(). I'm also not setting xdp.data_hard_start properly. It should work better with this small diff: diff --git a/net/core/dev.c b/net/core/dev.c index 9ed4569..d36ae8f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4289,6 +4289,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, u32 act = XDP_DROP; void *orig_data; int hlen, off; + u32 mac_len; if (skb_linearize(skb)) goto do_drop; @@ -4296,10 +4297,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, /* The XDP program wants to see the packet starting at the MAC * header. */ - hlen = skb_headlen(skb) + skb->mac_len; - xdp.data = skb->data - skb->mac_len; + mac_len = skb->data - skb_mac_header(skb); + hlen = skb_headlen(skb) + mac_len; + xdp.data = skb->data - mac_len; xdp.data_end = xdp.data + hlen; - xdp.data_hard_start = xdp.data - skb_headroom(skb); + xdp.data_hard_start = skb->data - skb_headroom(skb); orig_data = xdp.data; act = bpf_prog_run_xdp(xdp_prog, &xdp);
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