Commit 21c85974 authored by Xie He's avatar Xie He Committed by Jakub Kicinski
Browse files

net/packet: Improve the comment about LL header visibility criteria 



The "dev_has_header" function, recently added in
commit d5496990 ("net/packet: fix packet receive on L3 devices
without visible hard header"),
is more accurate as criteria for determining whether a device exposes
the LL header to upper layers, because in addition to dev->header_ops,
it also checks for dev->header_ops->create.

When transmitting an skb on a device, dev_hard_header can be called to
generate an LL header. dev_hard_header will only generate a header if
dev->header_ops->create is present.

Signed-off-by: default avatarXie He <xie.he.0141@gmail.com>
Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20210205224124.21345-1-xie.he.0141@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 163a1802

net/packet/af_packet.c

+2 −2
Original line number Diff line number Diff line
@@ -135,11 +135,11 @@ Resume 
On transmit:

------------



dev->header_ops != NULL

dev_has_header(dev) == true

   mac_header -> ll header

   data       -> ll header



dev->header_ops == NULL (ll header is invisible to us)

dev_has_header(dev) == false (ll header is invisible to us)

   mac_header -> data

   data       -> data