Re: [PATCH 4/9] drm/xen-front: Implement Xen event channel handling

[Oleksandr Andrushchenko]

On 02/23/2018 04:44 PM, Boris Ostrovsky wrote:
> On 02/23/2018 02:00 AM, Oleksandr Andrushchenko wrote:
> > On 02/23/2018 01:50 AM, Boris Ostrovsky wrote:
> > > On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote:
> > > > +
> > > > +static irqreturn_t evtchnl_interrupt_ctrl(int irq, void *dev_id)
> > > > +{
> > > > +    struct xen_drm_front_evtchnl *evtchnl = dev_id;
> > > > +    struct xen_drm_front_info *front_info = evtchnl->front_info;
> > > > +    struct xendispl_resp *resp;
> > > > +    RING_IDX i, rp;
> > > > +    unsigned long flags;
> > > > +
> > > > +    spin_lock_irqsave(&front_info->io_lock, flags);
> > > > +
> > > > +    if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
> > > > +        goto out;
> > > Do you need to check the state under lock? (in other routines too).
> > not really, will move out of the lock in interrupt handlers
> > other places (I assume you refer to be_stream_do_io)
>
> I was mostly referring to evtchnl_interrupt_evt().
ah, then we are on the same page: I will move the check
in interrupt handlers
> -boris
>
>
> > it is set under lock as a part of atomic operation, e.g.
> > we get a new request pointer from the ring and reset completion
> > So, those places still seem to be ok