On Tue, Feb 5, 2019 at 12:57 PM Stanislav Fomichev <s...@google.com> wrote: > > Currently, when eth_get_headlen calls flow dissector, it doesn't pass any > skb. Because we use passed skb to lookup associated networking namespace > to find whether we have a BPF program attached or not, we always use > C-based flow dissector in this case. > > The goal of this patch series is to add new networking namespace argument > to the eth_get_headlen and make BPF flow dissector programs be able to > work in the skb-less case. > > The series goes like this: > 1. introduce __init_skb and __init_skb_shinfo; those will be used to > initialize temporary skb > 2. introduce skb_net which can be used to get networking namespace > associated with an skb > 3. add new optional network namespace argument to __skb_flow_dissect and > plumb through the callers > 4. add new __flow_bpf_dissect which constructs temporary on-stack skb > (using __init_skb) and calls BPF flow dissector program
The main concern I see with this series is this cost of skb zeroing for every packet in the device driver receive routine, *independent* from the real skb allocation and zeroing which will likely happen later.
