Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Provide new socket option TCP_CCALGOOPT, which stands for TCP congestion
control algorithm options. The argument is variable length and is opaque
to TCP, forwarded directly to the algorithm's ctl_output method.

Provide new includes directory netinet/cc, where algorithm specific
headers can be installed.

The new API doesn't yet have any in tree consumers.

The original code written by lstewart.
Reviewed by: rrs, emax
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D711

DCTCP (Data Center TCP) implementation.

DCTCP congestion control algorithm aims to maximise throughput and minimise
latency in data center networks by utilising the proportion of Explicit
Congestion Notification (ECN) marked packets received from capable hardware as a
congestion signal.

Highlights:
Implemented as a mod_cc(4) module.
ECN (Explicit congestion notification) processing is done differently from
RFC3168.
Takes one-sided DCTCP into consideration where only one of the sides is using
DCTCP and other is using standard ECN.

IETF draft: http://tools.ietf.org/html/draft-bensley-tcpm-dctcp-00
Thesis report by Midori Kato: https://eggert.org/students/kato-thesis.pdf

Submitted by: Midori Kato <katoon@sfc.wide.ad.jp> and
Lars Eggert <lars@netapp.com>
with help and modifications from
hiren
Differential Revision: https://reviews.freebsd.org/D604
Reviewed by: gnn

Mention cc_cdg.

use .Mt to mark up email addresses consistently (final part)

PR: 191174
Submitted by: Franco Fichtner <franco at lastsummer.de>

Rename the cc.4 and cc.9 modular congestion control related man pages to
mod_cc.4 and mod_cc.9 respectively to avoid any possible confusion with the cc.1
gcc man page. Update references to these man pages where required.

Requested by: Grenville Armitage
Approved by: re (kib)
MFC after: 3 days

[mdoc] Fixed .Dt call.

Use the full and proper company name for Swinburne University of Technology
throughout the source tree.

Requested by: Grenville Armitage, Director of CAIA at Swinburne University of
Technology
MFC after: 3 days

Use a single list to simplify future maintenance and ensure all list items are
aligned the same (no functional change at the moment as both list items are the
same number of characters).

Sponsored by: FreeBSD Foundation
MFC after: 3 months
X-MFC with: 218912

Final commit to round out the "Five New TCP Congestion Control Algorithms for
FreeBSD" FreeBSD Foundation funded project.

- Add new man pages for the modular congestion control, Khelp and Hhook
frameworks (cc.4, cc.9, khelp.9 and hhook.9).

- Add new man pages for each available congestion control algorithm (cc_chd.4,
cc_cubic.4, cc_hd.4, cc_htcp.4, cc_newreno.4 and cc_vegas.4).

- Add a new man page for the Enhanced Round Trip Time (ERTT) Khelp module
(h_ertt.4).

- Update the TCP (tcp.4) man page to mention the TCP_CONGESTION socket option,
cross reference to cc.4 and remove references to the retired
"net.inet.tcp.newreno" sysctl MIB variable.

In collaboration with: David Hayes <dahayes at swin edu au> and
Grenville Armitage <garmitage at swin edu au>
Sponsored by: FreeBSD Foundation
MFC after: 3 months