Re: [PATCH v3 4/5] evtchn: convert domain event lock to an r/w one

[Julien Grall <julien@xxxxxxx>]

On 23/12/2020 12:57, Jan Beulich wrote:
> On 23.12.2020 12:22, Julien Grall wrote:
> > > 1) Neither evtchn_status() nor domain_dump_evtchn_info() appear to
> > > have a real need to acquire the per-domain lock. They could as well
> > > acquire the per-channel ones. (In the latter case this will then
> > > also allow inserting the so far missing process_pending_softirqs()
> > > call; it shouldn't be made with a lock held.)
> > I agree that evtchn_status() doesn't need to acquire the per-domain
> > lock. I am not entirely sure about domain_dump_evtchn_info() because
> > AFAICT the PIRQ tree (used by domain_pirq_to_irq()) is protected with
> > d->event_lock.
> It is, but calling it without the lock just to display the IRQ
> is not a problem afaict.
How so? Is the radix tree lookup safe against concurrent radix tree 
insertion/deletion?
Cheers,

--
Julien Grall