mac80211: track and share mesh BSSes among interfaces

Add a new global list of mesh BSSes for this host.  Each struct
mesh_local_bss contains parameters specific to a mesh instance,
as well as a list of interfaces participating in the MBSS.  This
will enable lookup of other interfaces on the host participating
in the same mesh.

Signed-off-by: Bob Copeland <bob@cozybit.com>

v2:
	drop can_share and don't add unshared MBSS to
	global list (Johannes)
mac80211: mesh: add function to tx on all other mbss ifaces

Add a function to rebroadcast mcast/bcast frames on other
interfaces when multiple interfaces are shared in an mbss.

Signed-off-by: Bob Copeland <bob@cozybit.com>
mac80211: use all MBSS interfaces for path selection

Change the HWMP path selection code to establish paths using
all interfaces participating in a shared mbss.  This means that
group-addressed action frames like PREQ will go out on each
interface, while individually addressed frames use whichever
interface has the destination as a peer.

When processing received frames, consider it a match if any
local interface in the mbss matches the target address.

Finally, mesh_path_lookup() now scans the path table on each
interface until a path (if any) is found so that paths can
be shared among the interfaces.

[ PERR/unicast frame handling fixes from Thomas Pedersen ]

Signed-off-by: Bob Copeland <bob@cozybit.com>

v2:
	kernel-doc fixes (Johannes)
mac80211: assign outgoing interface with nexthop

When updated mpath routing info is found, the new route
may be on a different interface (in the case of MBSS
sharing).

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mac80211: forward frames on correct mbss-shared interface

A forwarded frame may have a destination STA which resides
on a vif other than the RX interface. Have
mesh_nexthop_lookup() fill in the right outgoing sdata in
the skb control block.

Also update the congestion detection logic to take into
account a possibly different outgoing interface.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mac80211: notify bridge when leaving mesh

After turning carrier off, any parent bridge interface
needs to be notified. Otherwise we would see a panic when
attempting to transmit frames on a mesh interface which
hadn't yet been put down.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mac80211: make RMC per-mbss

The RMC was previously per-sdata, but it is sufficient for
one of the interfaces in a local mbss to receive a
multicast frame once.

Once multiple interfaces share the same mesh data forwarding
duties, we may inadvertently create a multicast routing loop
and have a corner case where a multicast frame is
retransmitted a few times too many.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mac80211: forward group frames on mbss-shared interfaces

When multiple local interfaces are in the same MBSS, we should
forward group-directed data frames received on one interface
for transmit on the other interfaces, so that the frames may be
seen on other channels.

Signed-off-by: Bob Copeland <bob@cozybit.com>
mac80211: add shared-mbss transmit path

Transmit locally-originated group data frames on every interface
so that members of the mesh on every channel will see the frame.

For individually-addressed frames, when we resolve the next
hop, the outgoing interface might be different than the
originator if the best path is on a different channel.
Requeue such frames on the correct interface's pending queue.

Signed-off-by: Bob Copeland <bob@cozybit.com>
mac08211: add shared-mbss receive path handling

If a destination interface is participating in a shared mbss, then
receive data frames on the correct interface (or all for mcast) when
passing frames to upper layers.

Signed-off-by: Bob Copeland <bob@cozybit.com>
{nl,mac}80211: specify MBSS sharing on/off

Allow the user to choose whether a newly joined MBSS
should be shared with other matching interfaces.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
{nl,mac}80211: allow mpath dump to span local MBSS

Allow the user to specify a flag
NL80211_ATTR_MPATH_DUMP_MBSS along with an mpath dump
request to dump all paths in the interface's mbss.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mac80211: ensure headroom when switching skb interface