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| author | Neal Cardwell <ncardwell@google.com> | 2015-02-06 16:04:39 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-02-08 01:03:12 -0800 |
| commit | a9b2c06dbef48ed31cff1764c5ce824829106f4f (patch) | |
| tree | 7e1dc6d03d3f2ba41a3a867fad3bf59c49665599 /include/linux/tcp.h | |
| parent | 032ee4236954eb214651cb9bfc1b38ffa8fd7a01 (diff) | |
| download | linux-a9b2c06dbef48ed31cff1764c5ce824829106f4f.tar.gz linux-a9b2c06dbef48ed31cff1764c5ce824829106f4f.tar.bz2 linux-a9b2c06dbef48ed31cff1764c5ce824829106f4f.zip | |
tcp: mitigate ACK loops for connections as tcp_request_sock
In the SYN_RECV state, where the TCP connection is represented by
tcp_request_sock, we now rate-limit SYNACKs in response to a client's
retransmitted SYNs: we do not send a SYNACK in response to client SYN
if it has been less than sysctl_tcp_invalid_ratelimit (default 500ms)
since we last sent a SYNACK in response to a client's retransmitted
SYN.
This allows the vast majority of legitimate client connections to
proceed unimpeded, even for the most aggressive platforms, iOS and
MacOS, which actually retransmit SYNs 1-second intervals for several
times in a row. They use SYN RTO timeouts following the progression:
1,1,1,1,1,2,4,8,16,32.
Reported-by: Avery Fay <avery@mixpanel.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/tcp.h')
| -rw-r--r-- | include/linux/tcp.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 67309ece0772..bcc828d3b9b9 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -115,6 +115,7 @@ struct tcp_request_sock { u32 rcv_isn; u32 snt_isn; u32 snt_synack; /* synack sent time */ + u32 last_oow_ack_time; /* last SYNACK */ u32 rcv_nxt; /* the ack # by SYNACK. For * FastOpen it's the seq# * after data-in-SYN. |