Re: (usagi-users 02296) IPv6 duplicate address bugfix

In article [ref] (at Sun, 30 Mar 2003 14:27:05 +0200), Simone Piunno [off-list ref] says:

When adding an IPv6 address to a given interface, I'm allowed to
add that address multiple time, e.g.:

[root@abulafia root]# ip addr add 3ffe:4242:4242::1 dev eth0
[root@abulafia root]# ip addr add 3ffe:4242:4242::1 dev eth0
[root@abulafia root]# ip addr add 3ffe:4242:4242::1 dev eth0
[root@abulafia root]# ip addr show dev eth0
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
    link/ether 00:48:54:1b:25:30 brd ff:ff:ff:ff:ff:ff
    inet6 3ffe:4242:4242::1/128 scope global 
    inet6 3ffe:4242:4242::1/128 scope global 
    inet6 3ffe:4242:4242::1/128 scope global 
    inet6 fe80::248:54ff:fe1b:2530/10 scope link

Apparently, this is not a stability problem, because I'm allowed to 
delete 3 times that address before receving a "not found" error,
but there's no reason to allow multiple instances of the same address 
on the same interface, so this is a bug nonetheless.

Bug is confirmed on:
  - 2.4.20
  - 2.5.66
  - latest -usagi

usagi code does not act like that.

In my environment,

# ip addr add 3ffe:4242:4242::1 dev eth0
# ip addr add 3ffe:4242:4242::1 dev eth0
RTNETLINK answers: No buffer space available
# ip addr add 3ffe:4242:4242::1 dev eth0
RTNETLINK answers: No buffer space available

And, patch does not seem optimal. I'd take a look at very soon.

-- 
Hideaki YOSHIFUJI @ USAGI Project [off-list ref]
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