[PATCH v2 net-next] tcp: add tracepoint trace_tcp_retransmit_synack()
From: Song Liu <hidden>
Date: 2017-10-30 21:41:44
Subsystem:
networking [general], networking [tcp], the rest, tracing · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
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. Note that, like many other tracepoints, this patch uses IS_ENABLED in TP_fast_assign macro, which triggers sparse warning like: ./include/trace/events/tcp.h:274:1: error: directive in argument list ./include/trace/events/tcp.h:281:1: error: directive in argument list However, there is no good solution to avoid these warnings. To the best of our knowledge, these warnings are harmless. Signed-off-by: Song Liu <redacted> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <redacted> --- 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 a69a34f..74d1c4d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c@@ -3781,6 +3781,7 @@ 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