Re: [Xen-devel] Re: [patch] netfront: unregister net device at backend_changed() if network_connect() failed

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 19/11/08 02:13, "Joe Jin" <joe.jin@xxxxxxxxxx> wrote:

>> One concern I have is that leaving an interface structure allocated but
>> unregistered is not a state we've previously handled in netfront, and could
>> cause bad kernel behaviour if, for example, the netif gets unprobed later.
>> 
> 
> I think if device initilise failed, we'd better release all resources like
> former's netif_free(): http://xen.markmail.org/message/2bp3xgsqzdofwoy6
> from patch description the patch tried to *"eliminates earlier workaround
> patch
> for an observed crash."*
> In fact the crashed caused by not unregister the device made the interface's
> state is NETREG_REGISTERED, when network_connect() failed, call free_netdev()
> would trigered BUG_ON, just add unregister_netdev() would solved the issue.

My point is, if you unregister_netdev() on failed network_connect(), and
then do it unconditionally again in netfront_remove(), you will BUG_ON() in
unregister_netdevice().

 -- Keir



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