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authorSong Liu <songliubraving@fb.com>2017-10-30 14:41:35 -0700
committerDavid S. Miller <davem@davemloft.net>2017-11-03 10:12:45 +0900
commitcf34ce3da1e41579296364509266c7dac573822a (patch)
tree621b3473cdd11c8a66a8c0c4819cad3974c32896 /net/ipv4
parent47d3d7ac656a1ffb9d0f0d3c845663ed6fd7e78d (diff)
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: Song Liu <songliubraving@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_output.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a85e8a282d17..06a0c89ffe40 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -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;
}