I just received a notification from patchwork that this patch was accepted.
This version of the patch does not address Sven's comments.
This first version also does not address the concern that I found after submitting the patch, which is that the soft interface netdev can be destroyed before this work finishes. This less likely race can lead to a similar problem, so I don't feel like this is the right solution.
Please withdraw this patch.
I've decided to move on to other things, so if someone else wants to pick this up, please feel free.
Thanks,
Andy