On Thu, Feb 13, 2025 at 7:19 AM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
>
> On 2/11/25 10:18 PM, Jason Xing wrote:
> > Support sw SCM_TSTAMP_SND case for bpf timestamping.
> >
> > Add a new sock_ops callback, BPF_SOCK_OPS_TS_SW_OPT_CB. This
> > callback will occur at the same timestamping point as the user
> > space's software SCM_TSTAMP_SND. The BPF program can use it to
> > get the same SCM_TSTAMP_SND timestamp without modifying the
> > user-space application.
> >
> > Based on this patch, BPF program will get the software
> > timestamp when the driver is ready to send the skb. In the
> > sebsequent patch, the hardware timestamp will be supported.
> >
> > Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
> > ---
> > include/linux/skbuff.h | 2 +-
> > include/uapi/linux/bpf.h | 4 ++++
> > net/core/skbuff.c | 9 ++++++++-
> > tools/include/uapi/linux/bpf.h | 4 ++++
> > 4 files changed, 17 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index 52f6e033e704..76582500c5ea 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -4568,7 +4568,7 @@ void skb_tstamp_tx(struct sk_buff *orig_skb,
> > static inline void skb_tx_timestamp(struct sk_buff *skb)
> > {
> > skb_clone_tx_timestamp(skb);
> > - if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
> > + if (skb_shinfo(skb)->tx_flags & (SKBTX_SW_TSTAMP | SKBTX_BPF))
> > skb_tstamp_tx(skb, NULL);
> > }
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 68664ececdc0..b3bd92281084 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7039,6 +7039,10 @@ enum {
> > * dev layer when SK_BPF_CB_TX_TIMESTAMPING
> > * feature is on.
> > */
> > + BPF_SOCK_OPS_TS_SW_OPT_CB, /* Called when skb is about to send
> > + * to the nic when SK_BPF_CB_TX_TIMESTAMPING
> > + * feature is on.
> > + */
> > };
> >
> > /* 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 7bac5e950e3d..d80d2137692f 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -5557,6 +5557,7 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
> > }
> >
> > static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
> > + struct skb_shared_hwtstamps *hwts,
>
> s/hwts/hwtstamps/
> Use the same argument name as all other functions in this file. Its caller is
> using hwtstamps as the argument name also. Easier to follow.
>
> Probably the same for the skb_tstamp_tx_report_so_timestamping().
Got it. Next version will include this modification.
Thanks,
Jason
>
> > struct sock *sk,
> > int tstype)
> > {
> > @@ -5566,6 +5567,11 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
> > case SCM_TSTAMP_SCHED:
> > op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
> > break;
> > + case SCM_TSTAMP_SND:
> > + if (hwts)
> > + return;
> > + op = BPF_SOCK_OPS_TS_SW_OPT_CB;
> > + break;
> > default:
> > return;
> > }
> > @@ -5586,7 +5592,8 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
> > return;
> >
> > if (skb_shinfo(orig_skb)->tx_flags & SKBTX_BPF)
> > - skb_tstamp_tx_report_bpf_timestamping(orig_skb, sk, tstype);
> > + skb_tstamp_tx_report_bpf_timestamping(orig_skb, hwtstamps,
> > + sk, tstype);
> >
> > if (!skb_tstamp_tx_report_so_timestamping(orig_skb, hwtstamps, tstype))
> > return;
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index eed91b7296b7..9bd1c7c77b17 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -7029,6 +7029,10 @@ enum {
> > * dev layer when SK_BPF_CB_TX_TIMESTAMPING
> > * feature is on.
> > */
> > + BPF_SOCK_OPS_TS_SW_OPT_CB, /* Called when skb is about to send
> > + * to the nic when SK_BPF_CB_TX_TIMESTAMPING
> > + * feature is on.
> > + */
> > };
> >
> > /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
>
