[libvirt-users] [netcf]IFF_RUNNING flag on a bridge device

[Laine Stump]

On 05/27/2014 09:07 AM, Jianwei Hu wrote:
> Hi All,
>
> I have one netcf question, please help me to resolve it, thanks.
>
> I can set a IFF_RUNNING flag to a bridge device which are no interface device attached. What status of a flag on a bridge device in current kernel?(w/o interface), is this a new change in kernel or other component? In netcf, but there is a patch to fix that flag issue, I can't understand it.  
>
> fix wrong status of bridge devices
> The IFF_RUNNING flag is not set on a bridge device if there are no devices attached to it. So bridges without attached devices are reported as inactive. Destroying inactive devices leads to an error and thus the device can't be removed (easily) from the operating system. This patch checks if the device is a bridge and if so ignores the IFF_RUNNING flag. 

Well, I took the patch submitter (Hendrik Schwartke <hendrik at os-t.de>)
at his word about the brokenness, and the patch didn't *hurt* anything,
so I pushed it. But now that I try it out I see that, at least on the
kernel version in Fedora 20 (and RHEL6.6) IFF_RUNNING *is* set when a
bridge device is ifconfiged up.

So I'm not sure what had caused the original problem, maybe Hendrik can
eluminate us on that, but it makes sense (since the whole reason for
adding the check of IFF_RUNNING in the first place was to notice when an
ethernet is unplugged, but a bridge is *never* plugged or unplugged in
the sense that we're looking for) and doesn't harm anything (and
apparently does fix something for Hendrik).

BTW, when you have netcf-specific questions of patches, you can send
them to netcf-devel at lists.fedorahosted.org