netdev - Re: [PATCH net-next 3/9] net-timestamp: introduce TS_SW_OPT

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Message-ID: <CAL+tcoBxdcEyigGjdPLM=LzDwx-q87t+_CewF7PvxRSavi8Utw@mail.gmail.com>
Date: Wed, 9 Oct 2024 07:08:04 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, dsahern@...nel.org, willemdebruijn.kernel@...il.com, 
	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, bpf@...r.kernel.org, 
	netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next 3/9] net-timestamp: introduce TS_SW_OPT_CB to
 generate driver timestamp

On Wed, Oct 9, 2024 at 3:13 AM Vadim Fedorenko
<vadim.fedorenko@...ux.dev> wrote:
>
> On 08/10/2024 10:51, Jason Xing wrote:
> > From: Jason Xing <kernelxing@...cent.com>
> >
> > When the skb is about to send from driver to nic, we can print timestamp
> > by setting BPF_SOCK_OPS_TS_SW_OPT_CB in bpf program.
> >
> > Signed-off-by: Jason Xing <kernelxing@...cent.com>
> > ---
> >   include/uapi/linux/bpf.h       | 5 +++++
> >   net/core/skbuff.c              | 8 +++++++-
> >   tools/include/uapi/linux/bpf.h | 5 +++++
> >   3 files changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 3cf3c9c896c7..0d00539f247a 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7024,6 +7024,11 @@ enum {
> >                                        * feature is on. It indicates the
> >                                        * recorded timestamp.
> >                                        */
> > +     BPF_SOCK_OPS_TS_SW_OPT_CB,      /* Called when skb is about to send
> > +                                      * to the nic 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 e697f50d1182..8faaa96c026b 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -5556,11 +5556,17 @@ static bool bpf_skb_tstamp_tx(struct sock *sk, u32 scm_flag,
> >               case SCM_TSTAMP_SCHED:
> >                       cb_flag = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
> >                       break;
> > +             case SCM_TSTAMP_SND:
> > +                     cb_flag = BPF_SOCK_OPS_TS_SW_OPT_CB;
> > +                     break;
> >               default:
> >                       return true;
> >               }
> >
> > -             tstamp = ktime_to_timespec64(ktime_get_real());
> > +             if (hwtstamps)
> > +                     tstamp = ktime_to_timespec64(hwtstamps->hwtstamp);
> > +             else
> > +                     tstamp = ktime_to_timespec64(ktime_get_real());
>
> Looks like this chunk belongs to another patch?

Makes sense. I could remove it here and write them when we need to
implement hwtstamp logic.

Thanks,
Jason