Re: [PATCH v2 1/5] net: timestamp: add helper returning skb's tx tstamp

[Jason Xing <kerneljasonxing@gmail.com>]

On Wed, Jun 4, 2025 at 4:41 PM Pavel Begunkov <asml.silence@gmail.com> wrote:
>
> Add a helper function skb_get_tx_timestamp() that returns a tx timestamp
> associated with an skb from an queue queue.
>
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>

Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>

Thanks,
Jason

> ---
>  include/net/sock.h |  4 ++++
>  net/socket.c       | 43 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+)
>
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 92e7c1aae3cc..1cd288880ab3 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -2677,6 +2677,10 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
>  void __sock_recv_wifi_status(struct msghdr *msg, struct sock *sk,
>                              struct sk_buff *skb);
>
> +bool skb_has_tx_timestamp(struct sk_buff *skb, const struct sock *sk);
> +bool skb_get_tx_timestamp(struct sk_buff *skb, struct sock *sk,
> +                         struct timespec64 *ts);
> +
>  static inline void
>  sock_recv_timestamp(struct msghdr *msg, struct sock *sk, struct sk_buff *skb)
>  {
> diff --git a/net/socket.c b/net/socket.c
> index 9a0e720f0859..e9c8f3074fe1 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -843,6 +843,49 @@ static void put_ts_pktinfo(struct msghdr *msg, struct sk_buff *skb,
>                  sizeof(ts_pktinfo), &ts_pktinfo);
>  }
>
> +bool skb_has_tx_timestamp(struct sk_buff *skb, const struct sock *sk)
> +{
> +       const struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
> +       u32 tsflags = READ_ONCE(sk->sk_tsflags);
> +
> +       if (serr->ee.ee_errno != ENOMSG ||
> +          serr->ee.ee_origin != SO_EE_ORIGIN_TIMESTAMPING)
> +               return false;
> +
> +       /* software time stamp available and wanted */
> +       if ((tsflags & SOF_TIMESTAMPING_SOFTWARE) && skb->tstamp)
> +               return true;
> +       /* hardware time stamps available and wanted */
> +       return (tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) &&
> +               skb_hwtstamps(skb)->hwtstamp;
> +}
> +
> +bool skb_get_tx_timestamp(struct sk_buff *skb, struct sock *sk,
> +                         struct timespec64 *ts)
> +{
> +       u32 tsflags = READ_ONCE(sk->sk_tsflags);
> +       ktime_t hwtstamp;
> +       int if_index = 0;
> +
> +       if ((tsflags & SOF_TIMESTAMPING_SOFTWARE) &&
> +           ktime_to_timespec64_cond(skb->tstamp, ts))
> +               return true;
> +
> +       if (!(tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) ||
> +           skb_is_swtx_tstamp(skb, false))
> +               return false;
> +
> +       if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP_NETDEV)
> +               hwtstamp = get_timestamp(sk, skb, &if_index);
> +       else
> +               hwtstamp = skb_hwtstamps(skb)->hwtstamp;
> +
> +       if (tsflags & SOF_TIMESTAMPING_BIND_PHC)
> +               hwtstamp = ptp_convert_timestamp(&hwtstamp,
> +                                               READ_ONCE(sk->sk_bind_phc));
> +       return ktime_to_timespec64_cond(hwtstamp, ts);
> +}
> +
>  /*
>   * called from sock_recv_timestamp() if sock_flag(sk, SOCK_RCVTSTAMP)
>   */
> --
> 2.49.0
>
>