diff options
| -rw-r--r-- | net/packet/af_packet.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index af6c93ed9fa0..2d5d5fbb435c 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -93,12 +93,15 @@ /* Assumptions: - - if device has no dev->hard_header routine, it adds and removes ll header - inside itself. In this case ll header is invisible outside of device, - but higher levels still should reserve dev->hard_header_len. - Some devices are enough clever to reallocate skb, when header - will not fit to reserved space (tunnel), another ones are silly - (PPP). + - If the device has no dev->header_ops, there is no LL header visible + above the device. In this case, its hard_header_len should be 0. + The device may prepend its own header internally. In this case, its + needed_headroom should be set to the space needed for it to add its + internal header. + For example, a WiFi driver pretending to be an Ethernet driver should + set its hard_header_len to be the Ethernet header length, and set its + needed_headroom to be (the real WiFi header length - the fake Ethernet + header length). - packet socket receives packets with pulled ll header, so that SOCK_RAW should push it back. |