ifplugd does not detect link up

Denys Vlasenko vda.linux at googlemail.com
Thu Jan 7 13:52:04 UTC 2010


On Thu, Jan 7, 2010 at 1:41 PM, Ladislav Michl <Ladislav.Michl at seznam.cz> wrote:
> Busybox's ifplugd was a bit modified since derived from its original and now
> it no longer works with smc91x (linux-2.6.32). After cable removal and
> interface deconfiguration so subsequent link up is reported. Change
> responsible for this behaviour is listed bellow. Could we revert this change
> (or eventually add an option for that)?

I want it to be documented. I think I disabled it because
I was puzzled when ifplugd kept upping the interface.

Let's confirm it: the device which you have problem with
says "using IFF_RUNNING detection mode", right?

It means that when cable is unplugged, interface cannot be "upped",
and this is used to detect that. With unfortunate effect that now admin
cannot set "up/down" status as he pleases.

Can you check this by doing "ip l set dev ethN up; ip l l"
and seeing whether device is up or not, with and without cable inserted?

Then we can better document it in code and in help text. For one,
I'd say -a option "Don't up interface automatically"
should explain that it is generally useful, but must not be used
with devices which require IFF_RUNNING.

And we can remove that #if 0 then.

How about this?
--
vda


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