Description of problem:
When an ipv6 link-local address is added (either automatically or manually) to a
prism54pci (mac80211) device, the address will always be marked "tentative", and
a "duplicate address detected!" message will be output in syslog.  This is
definitely not a duplicate address.  It looks like the device is seeing its own
broadcast packets, that the kernel sent out to perform ipv6 Neighbor Discovery.
 This may be similar to this bug:
http://bughost.org/bugzilla/show_bug.cgi?id=265

Version-Release number of selected component (if applicable):
kernel-2.6.21-1.3228.fc7

How reproducible:
always

Steps to Reproduce:
1. flush ipv6 addrs from the device (for consistency)
# ip -6 addr flush wlan1
2. manually add a unique ipv6 addr to the device
# ip -6 addr add fe80::209:5bff:feea:c06f/64 dev wlan1 scope link
3. look in syslog for the "duplicate address detected!" message
4. see that the address has been marked tentative
# ip -6 addr show wlan1
7: wlan1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::209:5bff:feea:c06f/64 scope link tentative 
       valid_lft forever preferred_lft forever

Actual results:
"duplicate address detected!" in syslog, address is marked tentative and is unusable

Expected results:
no duplicate address detected, address not marked tentative

Additional info:
attached a wireshark capture of the ipv6 broadcast packets that the device sees
when the address is added