On Sat, Jan 25, 2025 at 8:50 AM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
>
> On 1/20/25 5:28 PM, Jason Xing wrote:
> > Introduce the callback to correlate tcp_sendmsg timestamp with other
> > three points (SND/SW/ACK). We can let bpf trace the beginning of
> > tcp_sendmsg_locked() and fetch the socket addr, so that in
> > tcp_tx_timestamp() we can correlate the tskey with the socket addr.
> > It is accurate since they are under the protect of socket lock.
> > More details can be found in the selftest.
> >
> > Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
> > ---
> > include/uapi/linux/bpf.h | 3 +++
> > net/ipv4/tcp.c | 1 +
> > tools/include/uapi/linux/bpf.h | 3 +++
> > 3 files changed, 7 insertions(+)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 3b9bfc88345c..55c74fa18163 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7042,6 +7042,9 @@ enum {
> > * feature is on. It indicates the
> > * recorded timestamp.
> > */
> > + BPF_SOCK_OPS_TS_TCP_SND_CB, /* Called when every tcp_sendmsg
> > + * syscall is triggered
> > + */
>
> I recall we agreed in v5 to adjust the "TCP_" naming part because it will be
> used in UDP also. Like completely remove the "TCP_" from the name?
Right. The thing is that, after that discussion, I altered my thoughts
because I'm not so sure if I need this for UDP (I need more time to
think about the UDP case) which can be trace by fentry, sorry.
I will follow your instructions to remove "TCP_".
Thanks,
Jaosn
>
> > };
> >
> > /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
> > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> > index 0a41006b10d1..49e489c346ea 100644
> > --- a/net/ipv4/tcp.c
> > +++ b/net/ipv4/tcp.c
> > @@ -500,6 +500,7 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc)
> > tcb->txstamp_ack_bpf = 1;
> > shinfo->tx_flags |= SKBTX_BPF;
> > shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
> > + bpf_skops_tx_timestamping(sk, skb, BPF_SOCK_OPS_TS_TCP_SND_CB);
> > }
> > }
> >
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index b463aa9c27da..38fc04a7ac20 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -7035,6 +7035,9 @@ enum {
> > * feature is on. It indicates the
> > * recorded timestamp.
> > */
> > + BPF_SOCK_OPS_TS_TCP_SND_CB, /* Called when every tcp_sendmsg
> > + * syscall is triggered
> > + */
> > };
> >
> > /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
>
