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.
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 :)
--
Dan Smith
IBM Linux Technology Center
email: danms@xxxxxxxxxx
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