CCing key audience of the patch.
Thanks,
Song
> On Oct 24, 2017, at 4:57 PM, Song Liu <songliubrav...@fb.com> wrote:
>
> This tracepoint can be used to trace synack retransmits. It maintains
> pointer to struct request_sock.
>
> We cannot simply reuse trace_tcp_retransmit_skb() here, because the
> sk here is the LISTEN socket. The IP addresses and ports should be
> extracted from struct request_sock.
>
> Signed-off-by: Song Liu <songliubrav...@fb.com>
> ---
> include/trace/events/tcp.h | 56 ++++++++++++++++++++++++++++++++++++++++++++++
> net/ipv4/tcp_output.c | 1 +
> 2 files changed, 57 insertions(+)
>
> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
> index 03699ba..07cccca 100644
> --- a/include/trace/events/tcp.h
> +++ b/include/trace/events/tcp.h
> @@ -237,6 +237,62 @@ TRACE_EVENT(tcp_set_state,
> show_tcp_state_name(__entry->newstate))
> );
>
> +TRACE_EVENT(tcp_retransmit_synack,
> +
> + TP_PROTO(const struct sock *sk, const struct request_sock *req),
> +
> + TP_ARGS(sk, req),
> +
> + TP_STRUCT__entry(
> + __field(const void *, skaddr)
> + __field(const void *, req)
> + __field(__u16, sport)
> + __field(__u16, dport)
> + __array(__u8, saddr, 4)
> + __array(__u8, daddr, 4)
> + __array(__u8, saddr_v6, 16)
> + __array(__u8, daddr_v6, 16)
> + ),
> +
> + TP_fast_assign(
> + struct inet_request_sock *ireq = inet_rsk(req);
> + struct in6_addr *pin6;
> + __be32 *p32;
> +
> + __entry->skaddr = sk;
> + __entry->req = req;
> +
> + __entry->sport = ireq->ir_num;
> + __entry->dport = ntohs(ireq->ir_rmt_port);
> +
> + p32 = (__be32 *) __entry->saddr;
> + *p32 = ireq->ir_loc_addr;
> +
> + p32 = (__be32 *) __entry->daddr;
> + *p32 = ireq->ir_rmt_addr;
> +
> +#if IS_ENABLED(CONFIG_IPV6)
> + if (sk->sk_family == AF_INET6) {
> + pin6 = (struct in6_addr *)__entry->saddr_v6;
> + *pin6 = ireq->ir_v6_loc_addr;
> + pin6 = (struct in6_addr *)__entry->daddr_v6;
> + *pin6 = ireq->ir_v6_rmt_addr;
> + } else
> +#endif
> + {
> + pin6 = (struct in6_addr *)__entry->saddr_v6;
> + ipv6_addr_set_v4mapped(ireq->ir_loc_addr, pin6);
> + pin6 = (struct in6_addr *)__entry->daddr_v6;
> + ipv6_addr_set_v4mapped(ireq->ir_rmt_addr, pin6);
> + }
> + ),
> +
> + TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c
> daddrv6=%pI6c",
> + __entry->sport, __entry->dport,
> + __entry->saddr, __entry->daddr,
> + __entry->saddr_v6, __entry->daddr_v6)
> +);
> +
> #endif /* _TRACE_TCP_H */
>
> /* This part must be outside protection */
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 1f01f4c..6a728a5 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -3735,6 +3735,7 @@ int tcp_rtx_synack(const struct sock *sk, struct
> request_sock *req)
> __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
> if (unlikely(tcp_passive_fastopen(sk)))
> tcp_sk(sk)->total_retrans++;
> + trace_tcp_retransmit_synack(sk, req);
> }
> return res;
> }
> --
> 2.9.5
>
