kern/105945: Address can disappear from network interface

[Yar Tikhiy]

>Number:         105945
>Category:       kern
>Synopsis:       Address can disappear from network interface
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Nov 28 10:40:12 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Yar Tikhiy
>Release:        FreeBSD 7.0-CURRENT i386
>Organization:
none
>Environment:

	CURRENT and 6-STABLE

>Description:
	
	If a cloned interface is destroyed, recreated, and assigned
	an address without a delay, the address will disappear in
	a moment.  Moreover, a delay not longer than 0.1 sec between
	destruction and recreation doesn't seem to affect the issue.

>How-To-Repeat:

dg6# cat lo.sh
ifconfig lo5 destroy
ifconfig lo5 create 127.1.1.$1/24 mtu ${1}00
ifconfig lo5
echo almost there...
echo
sleep 1
ifconfig lo5
echo

dg6# sh lo.sh 100
ifconfig: interface lo5 does not exist
lo5: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 10000
        inet 127.1.1.100 netmask 0xffffff00
almost there...

lo5: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 10000
        inet 127.1.1.100 netmask 0xffffff00

dg6# sh lo.sh 101
lo5: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 10100
        inet 127.1.1.101 netmask 0xffffff00
almost there...

lo5: flags=8048<LOOPBACK,RUNNING,MULTICAST> mtu 10100

dg6# sh lo.sh 102
lo5: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 10200
        inet 127.1.1.102 netmask 0xffffff00
almost there...

lo5: flags=8048<LOOPBACK,RUNNING,MULTICAST> mtu 10200

dg6#


As the cookie stored in mtu shows, we are not setting parameters
on the dying instance of the interface -- IP just disappears from
the new instance.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: