On Sun, Sep 05, 2021 at 05:36:23PM +0300, Gal Pressman wrote:

quoted

I can't say if it is needed or not, just wanted to understand why you need
complexity in destroy_cq path.

Well, as I said, I don't think the restrack protection is enough in this case as
it isn't aware of the concurrent eq flow.

I guess I can put a synchronize_irq() on destroy_cq flow to get rid of the race.

That is a better choice that synchronize_rcu(), IIRC

synchronize_rcu should be avoided compared to all other forms of
synchronization because it can take seconds per call to complete, and
in a reasonable verbs app this means potentially minutes to close the
verbs FD and destroy many CQs.

Jason