Ugh.  I just realized that I was missing a MODULE_LICENSE("GPL"); for
this new module, otherwise module load fails to find the link for
cancel_work_sync.

---
netpoll: Add missing module license for netpoll_targets

Add a missing module license declaration to netpoll_targets that allows
it to use exported symbols (cancel_work_sync).

Signed-off-by: Mike Waychison <redacted>

diff --git a/net/core/netpoll_targets.c b/net/core/netpoll_targets.c
index 5fc84f8c..0887268 100644
--- a/net/core/netpoll_targets.c
+++ b/net/core/netpoll_targets.c

@@ -747,3 +747,4 @@ void unregister_netpoll_targets(struct netpoll_targets *nts)
 }
 EXPORT_SYMBOL_GPL(unregister_netpoll_targets);

+MODULE_LICENSE("GPL");