Caller or callee setting skb->network_header?

Hi,

For an .ndo_start_xmit handler, can the callee rely on the caller
setting the skb network header?

Or should the callee set it before performing any
skb_network_header()/ip_hdr()/ipv6_hdr()/... calls?

Cheers, Linus

PS: Currently looking at batman-adv's ndo_start_xmit handler
"interface_tx()", whether an skb_set_network_header() should be
added there as it uses ip_hdr()/ipv6_hdr() later
(-> batadv_mcast_forw_mode_check_ipv{4,6}()). Testing this in
VMs it seemed to be set correctly by the caller, but wanted to
check whether this can or shouldn't be relied on.