Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC/backport core kernel and userspace parts of r237263 (TCP_OFFLOAD
rework). MFC r237563, r239511, r243603, r245915, r245916, r245919,
r245921, r245922, r245924, r245925, r245932, r245934 too.

Build tested with make universe.

r237263:
- Updated TOE support in the kernel.
...

r237563:
Fix clang warning when compiling iw_cxgb.

r239511:
Correctly handle the case where an inp has already been dropped by the time
the TOE driver reports that an active open failed. toe_connect_failed is
supposed to handle this but it should be provided the inpcb instead of the
tcpcb which may no longer be around.

r243603:
Make sure that tcp_timer_activate() correctly sees TCP_OFFLOAD (or not).

r245915:
Heed SO_NO_OFFLOAD.

r245916:
Teach toe_4tuple_check() to deal with IPv6 4-tuples too.

r245919:
Add TCP_OFFLOAD hook in syncache_respond for IPv6 too, just like the one
that exists for IPv4.

r245921:
There is no need to call into the TOE driver twice in pru_rcvd (tod_rcvd
and then tod_output right after that).

r245922:
Avoid NULL dereference in nd6_storelladdr when no mbuf is provided. It
is called this way from a couple of places in the OFED code. (toecore
calls it too but that's going to change shortly).

r245924:
Move lle_event to if_llatbl.h

lle_event replaced arp_update_event after the ARP rewrite and ended up
in if_ether.h simply because arp_update_event used to be there too.
IPv6 neighbor discovery is going to grow lle_event support and this is a
good time to move it to if_llatbl.h.

The two in-tree consumers of this event - OFED and toecore - are not
affected.

r245925:
Generate lle_event in the IPv6 neighbor discovery code too.

r245932:
Teach toe_l2_resolve to resolve IPv6 destinations too.

r245934:
Add checks for SO_NO_OFFLOAD in a couple of places that I missed earlier
in r245915.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Modify most routines returning 'struct ifaddr *' to return references
rather than pointers, requiring callers to properly dispose of those
references. The following routines now return references:

ifaddr_byindex
ifa_ifwithaddr
ifa_ifwithbroadaddr
ifa_ifwithdstaddr
ifa_ifwithnet
ifaof_ifpforaddr
ifa_ifwithroute
ifa_ifwithroute_fib
rt_getifa
rt_getifa_fib
IFP_TO_IA
ip_rtaddr
in6_ifawithifp
in6ifa_ifpforlinklocal
in6ifa_ifpwithaddr
in6_ifadd
carp_iamatch6
ip6_getdstifaddr

Remove unused macro which didn't have required referencing:

IFP_TO_IA6

This closes many small races in which changes to interface
or address lists while an ifaddr was in use could lead to use of freed
memory (etc). In a few cases, add missing if_addr_list locking
required to safely acquire references.

Because of a lack of deep copying support, we accept a race in which
an in6_ifaddr pointed to by mbuf tags and extracted with
ip6_getdstifaddr() doesn't hold a reference while in transmit. Once
we have mbuf tag deep copy support, this can be fixed.

Reviewed by: bz
Obtained from: Apple, Inc. (portions)
MFC after: 6 weeks (portions)

This main goals of this project are:
1. separating L2 tables (ARP, NDP) from the L3 routing tables
2. removing as much locking dependencies among these layers as
possible to allow for some parallelism in the search operations
3. simplify the logic in the routing code,

The most notable end result is the obsolescent of the route
cloning (RTF_CLONING) concept, which translated into code reduction
in both IPv4 ARP and IPv6 NDP related modules, and size reduction in
struct rtentry{}. The change in design obsoletes the semantics of
RTF_CLONING, RTF_WASCLONE and RTF_LLINFO routing flags. The userland
applications such as "arp" and "ndp" have been modified to reflect
those changes. The output from "netstat -r" shows only the routing
entries.

Quite a few developers have contributed to this project in the
past: Glebius Smirnoff, Luigi Rizzo, Alessandro Cerri, and
Andre Oppermann. And most recently:

- Kip Macy revised the locking code completely, thus completing
the last piece of the puzzle, Kip has also been conducting
active functional testing
- Sam Leffler has helped me improving/refactoring the code, and
provided valuable reviews
- Julian Elischer setup the perforce tree for me and has helped
me maintaining that branch before the svn conversion

Import basic common and iwarp kernel RDMA infrastructure.

Supported by: Chelsio Inc.