The 6lowpan.c file was missing an #include statement for 6lowpan.h.
Without it we get the following type of warnings:

net/bluetooth/6lowpan.c:320:5: warning: symbol 'bt_6lowpan_recv' was not declared. Should it be static?
net/bluetooth/6lowpan.c:737:5: warning: symbol 'bt_6lowpan_add_conn' was not declared. Should it be static?
net/bluetooth/6lowpan.c:805:5: warning: symbol 'bt_6lowpan_del_conn' was not declared. Should it be static?
net/bluetooth/6lowpan.c:878:5: warning: symbol 'bt_6lowpan_init' was not declared. Should it be static?
net/bluetooth/6lowpan.c:883:6: warning: symbol 'bt_6lowpan_cleanup' was not declared. Should it be static?
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This is initial version of
http://tools.ietf.org/html/draft-ietf-6lo-btle-00

By default the 6LoWPAN support is not activated and user
needs to tweak /sys/kernel/debug/bluetooth/hci0/6lowpan
file.

The kernel needs IPv6 support before 6LoWPAN is usable.
Signed-off-by: NJukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>