On Wed, 7 Dec 2011 17:21:22 +0200, "Michael S. Tsirkin" [off-list ref] wrote:

Fix theoretical races related to refill work:
1. After napi is disabled by ndo_stop, refill work
   can run and re-enable it.
2. Refill can reschedule itself, if this happens
   it can run after cancel_delayed_work_sync,
   and will access device after it is destroyed.

As a solution, add flags to track napi state and
to disable refill, and toggle them on start, stop
and remove; check these flags on refill.

Why isn't a "dont-readd" flag sufficient?

Cheers,
Rusty.