netdev - Re: [PATCH net-next v2 2/2] net: make SOF_TIMESTAMPING_RX

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Message-ID: <CAL+tcoBby-AfrjFB8cAj5qcVK2T45=q61f3Y+W9_KfQQdVa0Nw@mail.gmail.com>
Date: Thu, 29 Aug 2024 23:38:27 +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, 
	netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next v2 2/2] net: make SOF_TIMESTAMPING_RX_SOFTWARE
 feature per socket

On Thu, Aug 29, 2024 at 10:21 PM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> Jason Xing wrote:
> > From: Jason Xing <kernelxing@...cent.com>
> >
> > Like the previous patch in this series, we need to make sure that
> > we both set SOF_TIMESTAMPING_SOFTWARE and SOF_TIMESTAMPING_RX_SOFTWARE
> > flags together so that we can let the user parse the rx timestamp.
> >
> > One more important and special thing is that we should take care of
> > errqueue recv path because we rely on errqueue to get our timestamps
> > for sendmsg(). Or else, If the user wants to read when setting
> > SOF_TIMESTAMPING_TX_ACK, something like this, we cannot get timestamps,
> > for example, in TCP case. So we should consider those
> > SOF_TIMESTAMPING_TX_* flags.
> >
> > After this patch, we are able to pass the testcase 6 for IP and UDP
> > cases when running ./rxtimestamp binary.
> >
> > Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>
> > Signed-off-by: Jason Xing <kernelxing@...cent.com>
> > ---
> >  Documentation/networking/timestamping.rst |  7 +++++++
> >  include/net/sock.h                        |  7 ++++---
> >  net/bluetooth/hci_sock.c                  |  4 ++--
> >  net/core/sock.c                           |  2 +-
> >  net/ipv4/ip_sockglue.c                    |  2 +-
> >  net/ipv4/ping.c                           |  2 +-
> >  net/ipv6/datagram.c                       |  4 ++--
> >  net/l2tp/l2tp_ip.c                        |  2 +-
> >  net/l2tp/l2tp_ip6.c                       |  2 +-
> >  net/nfc/llcp_sock.c                       |  2 +-
> >  net/rxrpc/recvmsg.c                       |  2 +-
> >  net/socket.c                              | 11 ++++++++---
> >  net/unix/af_unix.c                        |  2 +-
> >  13 files changed, 31 insertions(+), 18 deletions(-)
> >
> > diff --git a/Documentation/networking/timestamping.rst b/Documentation/networking/timestamping.rst
> > index 5e93cd71f99f..93378b78c6dd 100644
> > --- a/Documentation/networking/timestamping.rst
> > +++ b/Documentation/networking/timestamping.rst
> > @@ -160,6 +160,13 @@ SOF_TIMESTAMPING_RAW_HARDWARE:
> >    Report hardware timestamps as generated by
> >    SOF_TIMESTAMPING_TX_HARDWARE when available.
> >
> > +Please note: previously, if an application starts first which turns on
> > +netstamp_needed_key, then another one only passing SOF_TIMESTAMPING_SOFTWARE
> > +could also get rx timestamp. Now we handle this case and will not get
> > +rx timestamp under this circumstance. We encourage that for each socket
> > +we should use the SOF_TIMESTAMPING_RX_SOFTWARE generation flag to time
> > +stamp the skb and use SOF_TIMESTAMPING_SOFTWARE report flag to tell
> > +the application.
>
> Don't mention previously. Readers will not be aware of when this
> Documentation was added.

Got it, I will remove it :)

>
> Also, nit: no "Please note". Else every paragraph can start with that,
> as each statement should be noteworthy.

I see.

>
> >
> >  1.3.3 Timestamp Options
> >  ^^^^^^^^^^^^^^^^^^^^^^^
> > diff --git a/include/net/sock.h b/include/net/sock.h
> > index cce23ac4d514..b8535692f340 100644
> > --- a/include/net/sock.h
> > +++ b/include/net/sock.h
> > @@ -2600,12 +2600,13 @@ static inline void sock_write_timestamp(struct sock *sk, ktime_t kt)
> >  }
> >
> >  void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
> > -                        struct sk_buff *skb);
> > +                        struct sk_buff *skb, bool errqueue);
> >  void __sock_recv_wifi_status(struct msghdr *msg, struct sock *sk,
> >                            struct sk_buff *skb);
>
> I suspect that the direction, ingress or egress, and thus whether the
> timestamp is to be queued on the error queue or not, can be inferred
> without exceptions from skb->pkt_type == PACKET_OUTGOING.
>
> That would avoid all this boilerplate argument passing.

Ah, good suggestions!! I will update it in the V3.

Thanks,
Jason