Re: [PATCH v4 11/13] xen/pvcalls: implement poll command

[Stefano Stabellini]

On Fri, 22 Sep 2017, Boris Ostrovsky wrote:
> > +static unsigned int pvcalls_front_poll_passive(struct file *file,
> > +					       struct pvcalls_bedata *bedata,
> > +					       struct sock_mapping *map,
> > +					       poll_table *wait)
> > +{
> > +	int notify, req_id, ret;
> > +	struct xen_pvcalls_request *req;
> > +
> > +	if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
> > +		     (void *)&map->passive.flags)) {
> > +		uint32_t req_id = READ_ONCE(map->passive.inflight_req_id);
> > +
> > +		if (req_id != PVCALLS_INVALID_ID &&
> > +		    READ_ONCE(bedata->rsp[req_id].req_id) == req_id)
> > +			return POLLIN | POLLRDNORM;
> 
> 
> Do we need to clear PVCALLS_FLAG_ACCEPT_INFLIGHT? Or do we expect a
> (subsequent?) accept() to do that?

No need to clear, here we only need to say whether there is data to read
or not. Subsequent accept calls will clear PVCALLS_FLAG_ACCEPT_INFLIGHT.

 
> > +
> > +		poll_wait(file, &map->passive.inflight_accept_req, wait);
> > +		return 0;
> > +	}
> > +
>