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Commit cf34ce3d authored by Song Liu's avatar Song Liu Committed by David S. Miller
Browse files

tcp: add tracepoint trace_tcp_retransmit_synack() 



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: default avatarSong Liu <songliubraving@fb.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 47d3d7ac

include/trace/events/tcp.h

+56 −0
Original line number Diff line number Diff line
@@ -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 */

net/ipv4/tcp_output.c

+1 −0
Original line number Diff line number Diff line
@@ -3782,6 +3782,7 @@ 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;

}