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Re: hotplugging /e/n/i "auto" interfaces

On Thu, Apr 08, 2004 at 20:11 +0100, J.D. Hood wrote:
> Now, the driver for this card may have been loaded before this
> point.   In that case there has already been a hotplug event for
> the interface and it has already been brought up.  Thus, trying
> to bring it up again will fail.  I am not sure what follows from
> that but let's assume that nothing bad happens, we don't need to
> edit any scripts to deal with nonzero exit status, etc.

If it has already been brought up, it will be listed in
/etc/network/ifstate. ifup will notice this and not run any commands
at all. Perhaps it will print an error message but I don't think it
should if you run it with -a.

> On the other hand, the driver for the card may not have been
> loaded.  In that case the attempt to bring up the interface may
> induce a modprobe of the driver module.  This will cause a hotplug
> event and hotplug will run ifup for the interface, causing deadlock
> because the interface is already in the process of being ifup'ped.

Well, firstly, I believe there exists some kind of locking which would
prevent this. I'm not sure though. But apart from this - when does
this situation occur? Is it when you have defined the interface name
as an alias for a module in /etc/modules.conf? I don't think it
happens otherwise.


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