On 4/18/2024 1:49 PM, Willem de Bruijn wrote: > 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. Ah i see. I got it . I will make two APIs . Makes sense. 1. One can check for clockid => switch => set 2. One can set it directly.
