794200d662
This patch makes passive Fast Open reverts the cwnd to default initial cwnd (10 packets) if the SYNACK timeout is spurious. Passive Fast Open uses a full socket during handshake so it can use the existing undo logic to detect spurious retransmission by recording the first SYNACK timeout in key state variable retrans_stamp. Upon receiving the ACK of the SYNACK, if the socket has sent some data before the timeout, the spurious timeout is detected by tcp_try_undo_recovery() in tcp_process_loss() in tcp_ack(). But if the socket has not send any data yet, tcp_ack() does not execute the undo code since no data is acknowledged. The fix is to check such case explicitly after tcp_ack() during the ACK processing in SYN_RECV state. In addition this is checked in FIN_WAIT_1 state in case the server closes the socket before handshake completes. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.