diff options
| author | Jesper Dangaard Brouer <brouer@redhat.com> | 2020-05-14 12:49:28 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-05-14 21:21:54 -0700 |
| commit | a075767bbdc659066b89be282c8377fa880e9dc4 (patch) | |
| tree | 9b7b752af8904ab5f8e2c67591cca1e7f571bc70 | |
| parent | 495de55f70199bd7ea09079c484283e58bf75c82 (diff) | |
net: XDP-generic determining XDP frame size
The SKB "head" pointer points to the data area that contains
skb_shared_info, that can be found via skb_end_pointer(). Given
xdp->data_hard_start have been established (basically pointing to
skb->head), frame size is between skb_end_pointer() and data_hard_start,
plus the size reserved to skb_shared_info.
Change the bpf_xdp_adjust_tail offset adjust of skb->len, to be a positive
offset number on grow, and negative number on shrink. As this seems more
natural when reading the code.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158945336804.97035.7164852191163722056.stgit@firesoul
| -rw-r--r-- | net/core/dev.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 4c91de39890a..f937a3ff668d 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4617,6 +4617,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, xdp->data_meta = xdp->data; xdp->data_end = xdp->data + hlen; xdp->data_hard_start = skb->data - skb_headroom(skb); + + /* SKB "head" area always have tailroom for skb_shared_info */ + xdp->frame_sz = (void *)skb_end_pointer(skb) - xdp->data_hard_start; + xdp->frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + orig_data_end = xdp->data_end; orig_data = xdp->data; eth = (struct ethhdr *)xdp->data; @@ -4640,14 +4645,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, skb_reset_network_header(skb); } - /* check if bpf_xdp_adjust_tail was used. it can only "shrink" - * pckt. - */ - off = orig_data_end - xdp->data_end; + /* check if bpf_xdp_adjust_tail was used */ + off = xdp->data_end - orig_data_end; if (off != 0) { skb_set_tail_pointer(skb, xdp->data_end - xdp->data); - skb->len -= off; - + skb->len += off; /* positive on grow, negative on shrink */ } /* check if XDP changed eth hdr such SKB needs update */ |