[ovs-dev] "brctl show" doesn't list attached interfaces

Tadaaki Nagao nagao at stratosphere.co.jp
Mon Oct 1 14:15:29 UTC 2012


Hi Pravin,

In "Re: [ovs-dev] "brctl show" doesn't list attached interfaces",
    Pravin Shelar <pshelar at nicira.com> wrote:
> On Thu, Sep 27, 2012 at 8:18 PM, Tadaaki Nagao <nagao at stratosphere.co.jp> wrote:
> > Hi,
> >
> > In "Re: [ovs-dev] "brctl show" doesn't list attached interfaces",
> >     Jesse Gross <jesse at nicira.com> wrote:
> >> I think it's the opposite problem - that OVS ports aren't appearing in
> >> brctl output.  There's a bug with namespaces on certain kernels when
> >> populating the sysfs entries that Pravin ran into so we don't do that
> >> on the theory that missing entries are better than crashing.
> >
> > In datapath/dp_sysfs_dp.c:ovs_dp_sysfs_add_dp() there's a similar NULL
> > check with the same "could panic" comment, which makes sense to me because
> > sysfs_create_group() is actually called after the check.
> >
> > --------8<--------cut here--------8<--------
> > #ifdef CONFIG_NET_NS
> >         /* Due to bug in 2.6.32 kernel, sysfs_create_group() could panic
> >          * in other namespace than init_net. Following check is to avoid it. */
> >         if (!kobj->sd)
> >                 return -ENOENT;
> > #endif
> >         /* Create /sys/class/net/<devname>/bridge directory. */
> >         err = sysfs_create_group(kobj, &bridge_group);
> > --------8<--------cut here--------8<--------
> >
> > OTOH, after the check in datapath/dp_sysfs_if.c:ovs_dp_sysfs_add_if()
> > there's no call to sysfs_create_group() as I mentioned in the first mail.
> > And that made me uncertain what the check is actually meant for...
> >
> right, there is no call to sysfs_crate_grp() when adding a interface,
> need to fix comment.
> But it does panic on 2.6.32 while creating sysfs hierarchy in
> sysfs_create_dir(). I am not sure which kernel does fixes this issue.

Thank you for your comments!

I've finally managed to create a test environment on LXC + CentOS 6.3
(kernel 2.6.32-279.9.1.el6.x86_64) and could reproduce a panic when
commenting out the NULL check in ovs_dp_sysfs_add_if().

> I will see if we could have better check here.

If there's something I can do here, please let me know.

> Thanks,
> Pravin.

Thanks,
Tadaaki Nagao <nagao at stratosphere.co.jp>
Stratosphere Inc.



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