Cong Wang [off-list ref] writes:

On Wed, Jul 8, 2020 at 5:35 AM Petr Machata [off-list ref] wrote:

quoted

Do you have another solution in mind here? I think the deadlock (in both
classification and qevents) is an issue, but really don't know how to
avoid it except by dropping the lock.

Ideally we should only take the lock once, but it clearly requires some
work to teach the dev_queue_xmit() in act_mirred not to acquire it again.

act_mirred does not acquire it though. The egress path does. And the
packet can traverse several mirred instances on several devices before
it gets to the deadlock. Currently I don't see a way to give the egress
path a way to know that the lock is already taken.

I'll think about it some more. For now I will at least fix the lack of
locking.