Abhishek Chauhan (ABC) wrote: > > > On 4/18/2024 1:11 PM, Willem de Bruijn wrote: > > Abhishek Chauhan (ABC) wrote: > >> > >> > >> On 4/18/2024 11:47 AM, Willem de Bruijn wrote: > >>> Abhishek Chauhan wrote: > >>>> mono_delivery_time was added to check if skb->tstamp has delivery > >>>> time in mono clock base (i.e. EDT) otherwise skb->tstamp has > >>>> timestamp in ingress and delivery_time at egress. > >>>> > >>>> Renaming the bitfield from mono_delivery_time to tstamp_type is for > >>>> extensibilty for other timestamps such as userspace timestamp > >>>> (i.e. SO_TXTIME) set via sock opts. > >>>> > >>>> As we are renaming the mono_delivery_time to tstamp_type, it makes > >>>> sense to start assigning tstamp_type based on enum defined > >>>> in this commit. > >>>> > >>>> Earlier we used bool arg flag to check if the tstamp is mono in > >>>> function skb_set_delivery_time, Now the signature of the functions > >>>> accepts tstamp_type to distinguish between mono and real time. > >>>> > >>>> In future tstamp_type:1 can be extended to support userspace timestamp > >>>> by increasing the bitfield. > >>>> > >>>> Link: https://lore.kernel.org/netdev/bc037db4-58bb-4861-ac31-a361a93841d3@xxxxxxxxx/ > >>>> Signed-off-by: Abhishek Chauhan <quic_abchauha@xxxxxxxxxxx> > >>> > >>>> +/** > >>>> + * tstamp_type:1 can take 2 values each > >>>> + * represented by time base in skb > >>>> + * 0x0 => real timestamp_type > >>>> + * 0x1 => mono timestamp_type > >>>> + */ > >>>> +enum skb_tstamp_type { > >>>> + SKB_CLOCK_REAL, /* Time base is skb is REALTIME */ > >>>> + SKB_CLOCK_MONO, /* Time base is skb is MONOTONIC */ > >>>> +}; > >>>> + > >>> > >>> Can drop the comments. These names are self documenting. > >> > >> Noted! . I will take care of this > >>> > >>>> /** > >>>> * DOC: Basic sk_buff geometry > >>>> * > >>>> @@ -819,7 +830,7 @@ typedef unsigned char *sk_buff_data_t; > >>>> * @dst_pending_confirm: need to confirm neighbour > >>>> * @decrypted: Decrypted SKB > >>>> * @slow_gro: state present at GRO time, slower prepare step required > >>>> - * @mono_delivery_time: When set, skb->tstamp has the > >>>> + * @tstamp_type: When set, skb->tstamp has the > >>>> * delivery_time in mono clock base (i.e. EDT). Otherwise, the > >>>> * skb->tstamp has the (rcv) timestamp at ingress and > >>>> * delivery_time at egress. > >>> > >>> Is this still correct? I think all egress does now annotate correctly > >>> as SKB_CLOCK_MONO. So when not set it always is SKB_CLOCK_REAL. > >>> > >> That is correct. > >> > >>>> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c > >>>> index 61119d42b0fd..a062f88c47c3 100644 > >>>> --- a/net/ipv4/tcp_output.c > >>>> +++ b/net/ipv4/tcp_output.c > >>>> @@ -1300,7 +1300,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, > >>>> tp = tcp_sk(sk); > >>>> prior_wstamp = tp->tcp_wstamp_ns; > >>>> tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); > >>>> - skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); > >>>> + skb_set_delivery_time(skb, tp->tcp_wstamp_ns, CLOCK_MONOTONIC); > >>> > >>> Multiple references to CLOCK_MONOTONIC left > >>> > >> I think i took care of all the references. Apologies if i didn't understand your comment here. > > > > On closer read, there is a type issue here. > > > > skb_set_delivery_time takes a u8 tstamp_type. But it is often passed > > a clockid_t, and that is also what the switch expects. > > > > But it does also get called with a tstamp_type in code like the > > following: > > > > + u8 tstamp_type = skb->tstamp_type; > > unsigned int hlen, ll_rs, mtu; > > ktime_t tstamp = skb->tstamp; > > struct ip_frag_state state; > > @@ -82,7 +82,7 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk, > > if (iter.frag) > > ip_fraglist_prepare(skb, &iter); > > > > - skb_set_delivery_time(skb, tstamp, mono_delivery_time); > > + skb_set_delivery_time(skb, tstamp, tstamp_type); > > > > So maybe we need two variants, one that takes a tstamp_type and one > > that tames a clockid_t? > > > > The first can be simple, not switch needed. Just apply the two stores. > I agree to what you are saying but clockid_t => points to int itself. > > For example :- > void qdisc_watchdog_init_clockid(struct qdisc_watchdog *wd, struct Qdisc *qdisc, > clockid_t clockid) > > qdisc_watchdog_init_clockid(wd, qdisc, CLOCK_MONOTONIC); => sch_api.c > qdisc_watchdog_init_clockid(&q->watchdog, sch, q->clockid); =>sch_etf.c (q->clockid is int) My concern is more that we use CLOCK_MONOTONIC and SKB_CLOCK_MONO (and other clocks) interchangeably, without invariant checks to make sure that they map onto the same integer value.
