Re: [PATCH net-next v4] net: Re-use and set mono_delivery_time bit for userspace tstamp packets

[Martin KaFai Lau]

On 3/13/24 1:59 PM, Abhishek Chauhan (ABC) wrote:
> > > I think all this is crying for another bit in skb to mean user_delivery_time
> > > (skb->tstamp depends on skb->sk->sk_clockid) while mono_delivery_time is the
> > > mono time either set by kernel-tcp or bpf.
> >
> > It does sound like the approach with least side effects.
> Martin and Willem , while we are discussing to use seperate bit per skb to check if its
> SO_TXTIME from userspace or (rcv) timestamp . I came across two flags used in skbuff
> called in filter framework
> @tc_at_ingress: used within tc_classify to distinguish in/egress
> @from_ingress: packet was redirected from the ingress path
>
> Since i believe the above testcase is based on redirecting from ingress to egress part
> why cant we use these already existing flags ? Please advice
>
> I am not completely sure if we can use these flags to solve the bpf problem or not.

I don't see how they are related. It can tell where a skb is at. It cannot tell 
what is in skb->tstamp.