dhclient cause up/down cycle after 239356 ?

[Peter Jeremy]

On 2012-Aug-21 19:42:17 +0300, Vitalij Satanivskij <satan at ukr.net> wrote:
>Look's like dhclient do down/up sequence -

Not intentionally.

>Aug 21 19:21:00 home kernel: fxp0: link state changed to UP
>Aug 21 19:21:01 home kernel: fxp0: link state changed to DOWN
>Aug 21 19:21:01 home dhclient: New IP Address (fxp0): xx.xx.xx.xx
>Aug 21 19:21:01 home dhclient: New Subnet Mask (fxp0): 255.255.255.0
>Aug 21 19:21:01 home dhclient: New Broadcast Address (fxp0): xx.xx.xx.xx
>Aug 21 19:21:01 home dhclient: New Routers (fxp0): xx.xx.xx.xx
>Aug 21 19:21:03 home kernel: fxp0: link state changed to UP

I can reproduce this behaviour - but only on fxp (i82559 in my case)
NICs.  My bge (BCM5750) and rl (RTL8139) NICs do not report the
spurious DOWN/UP.  (I don't normally run DHCP on any fxp interfaces,
so I didn't see it during my testing).

The problem appears to be the 
  $IFCONFIG $interface inet alias 0.0.0.0 netmask 255.0.0.0 broadcast 255.255.255.255 up
executed by /sbin/dhclient-script during PREINIT.  This is making the
fxp NIC reset the link (actually, assigning _any_ IP address to an fxp
NIC causes it to reset the link).  The post r239356 dhclient detects
the link going down and exits.

>Before r239356 iface just doing down/up without dhclient exit and
>everything work fine.

For you, anyway.  Failing to detect link down causes problems for me
because my dhclient was not seeing my cable-modem resets and therefore
failing to reacquire a DHCP lease.

-- 
Peter Jeremy
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