On Sun, 11 Dec 2011 16:44:29 +0200, "Michael S. Tsirkin" [off-list ref] wrote:

On Thu, Dec 08, 2011 at 03:07:29PM +1030, Rusty Russell wrote:

quoted

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

quoted

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.

I started with that, but here's the problem I wanted to
address:

- we run out of descriptors and schedule refill work
- ndo_close runs
- refill work runs
- ndo_open runs

(s/ndo_close/ndo_stop/)

You don't think we should do any refills on a closed device?  If so, we
simply move the refill-stop code into ndo_stop (aka virtnet_close), and
the refill-start code into ndo_open (aka. virtnet_open).  Right?

Orthogonally, the refill-stop code is still buggy, as you noted.  And
for self-rearming timers the pattern I've always used is a flag.

Or am I being obtuse again? :)
Rusty.