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 <songliubrav...@fb.com>
Acked-by: Alexei Starovoitov <a...@kernel.org>
Acked-by: Martin KaFai Lau <ka...@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 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
