netdev - Re: [PATCH net-next v3 04/14] net-timestamp: introduce TS_SCHED_OPT

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Message-ID: <CAL+tcoCtg7Yu3dAWMM4EY4ARE-Lg33CKEoVned6G9MnA0QuVUg@mail.gmail.com>
Date: Tue, 29 Oct 2024 09:30:00 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, dsahern@...nel.org, willemb@...gle.com, ast@...nel.org, 
	daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev, 
	eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	haoluo@...gle.com, jolsa@...nel.org, shuah@...nel.org, ykolal@...com, 
	bpf@...r.kernel.org, netdev@...r.kernel.org, 
	Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next v3 04/14] net-timestamp: introduce
 TS_SCHED_OPT_CB to generate dev xmit timestamp

On Tue, Oct 29, 2024 at 9:02 AM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> Jason Xing wrote:
> > From: Jason Xing <kernelxing@...cent.com>
> >
> > Introduce BPF_SOCK_OPS_TS_SCHED_OPT_CB flag so that we can decide to
> > print timestamps when the skb just passes the dev layer.
> >
> > Signed-off-by: Jason Xing <kernelxing@...cent.com>
> > ---
> >  include/uapi/linux/bpf.h       |  5 +++++
> >  net/core/skbuff.c              | 31 ++++++++++++++++++++++++++++++-
> >  tools/include/uapi/linux/bpf.h |  5 +++++
> >  3 files changed, 40 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index e8241b320c6d..324e9e40969c 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7013,6 +7013,11 @@ enum {
> >                                        * by the kernel or the
> >                                        * earlier bpf-progs.
> >                                        */
> > +     BPF_SOCK_OPS_TS_SCHED_OPT_CB,   /* Called when skb is passing through
> > +                                      * dev layer when SO_TIMESTAMPING
> > +                                      * feature is on. It indicates the
> > +                                      * recorded timestamp.
> > +                                      */
> >  };
> >
> >  /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
> > diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> > index 39309f75e105..e6a5c883bdc6 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -64,6 +64,7 @@
> >  #include <linux/mpls.h>
> >  #include <linux/kcov.h>
> >  #include <linux/iov_iter.h>
> > +#include <linux/bpf-cgroup.h>
> >
> >  #include <net/protocol.h>
> >  #include <net/dst.h>
> > @@ -5621,13 +5622,41 @@ static void skb_tstamp_tx_output(struct sk_buff *orig_skb,
> >       __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
> >  }
> >
> > +static void timestamp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
> > +{
> > +     struct bpf_sock_ops_kern sock_ops;
> > +
> > +     memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
> > +     if (sk_fullsock(sk)) {
> > +             sock_ops.is_fullsock = 1;
> > +             sock_owned_by_me(sk);
>
> Why this check?

I imitated the use of BPF_CGROUP_RUN_PROG_SOCK_OPS.

>
> This will usually be false, as timestamps are taken outside the
> protocol layers.

I will remove this if branch.

Thanks,
Jason