Quoting Dan Smith (danms@xxxxxxxxxx):
> SH> rw_lockt is effectively a spinlock, so I don't think you can sleep
> SH> here.
>
> Yep, thanks.
>
> >> + for_each_netdev(net, dev) {
> >> + if (!dev->netdev_ops->ndo_checkpoint)
> >> + continue;
>
> SH> Won't the checkpoint_obj() call checkpoint_netdev(), which will return
> SH> -EINVAL if ndo_checkpoint is not defined?
>
> Yes, but this isn't the only place that checkpoint_netdev() could be
> called (dev->peer in the veth example) so I figured that it would be
> best to test it there too before I blindly call a NULL function
> pointer. It should never happen, but seemed prudent.
>
> SH> But here you skip the checkpoint_obj() call (which seems wrong to
> SH> me). Which do you want to have happen?
>
> What the code is doing is "skipping any interfaces in a netns that
> don't have a checkpoint operation" but would fail if you called
> checkpoint_obj() on a veth peer that happened to be missing that
> operation for some reason.
>
> I suppose you could argue that we should fail in the netns case
> instead, which will make this a bit messier for things we get for
> "free" in a new netns, like sit0. If preferable, I can just add an
> ndo_checkpoint() to sit0 as well and simply checkpoint the presence of
> it until later when we decide if we care about it.
I think that's be better. Right now if we checkpoint a container with
macvlan restart will be bogus, right? We're trying to avoid any cases
where we can't tell, at checkpoint, that restart won't be right.
> SH> By hard-coding veth stuff into generic-sounding functions in
> SH> net/checkpoint_dev.c you seem to be assuming that only veth will
> SH> ever be supported for checkpoint/restart? what about macvlan?
> SH> (Not to mention that eventually we intend to support moving
> SH> physical nics into containers)
>
> No, that's not what I'm assuming. The only interface type I need to
> control with RTNL is veth right now. So, if you'd prefer a
> single-case of:
>
> if (type == veth)
> do_veth_message();
> else
> fail();
>
> to record the goal of having more types later I'll happily add that
> unreachable code to the patch :)
What I was asking is should do_veth_message() be in drivers/net/veth.c?
-serge
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