Merge branch 'rds-ha-failover-fixes'

Sowmini Varadhan says:

====================
RDS: TCP: HA/Failover fixes

This series contains a set of fixes for bugs exposed when
we ran the following in a loop between a test machine pair:

 while (1); do
   # modprobe rds-tcp on test nodes
   # run rds-stress in bi-dir mode between test machine pair
   # modprobe -r rds-tcp on test nodes
 done

rds-stress in bi-dir mode will cause both nodes to initiate
RDS-TCP connections at almost the same instant, exposing the
bugs fixed in this series.

Without the fixes, rds-stress reports sporadic packet drops,
and packets arriving out of sequence. After the fixes,we have
been able to run the  test overnight, without any issues.

Each patch has a detailed description of the root-cause fixed
by the patch.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>