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Re: [qemu-s390x] [PATCH v2 5/5] vfio-ccw: add handling for async channel
Re: [qemu-s390x] [PATCH v2 5/5] vfio-ccw: add handling for async channel instructions
Thu, 24 Jan 2019 11:37:08 +0100
On Thu, 24 Jan 2019 11:06:37 +0100
Cornelia Huck <address@hidden> wrote:
> On Wed, 23 Jan 2019 16:51:48 +0100
> Halil Pasic <address@hidden> wrote:
> > On Mon, 21 Jan 2019 12:03:54 +0100
> > Cornelia Huck <address@hidden> wrote:
> > > Add a region to the vfio-ccw device that can be used to submit
> > > asynchronous I/O instructions. ssch continues to be handled by the
> > > existing I/O region; the new region handles hsch and csch.
> > >
> > > Interrupt status continues to be reported through the same channels
> > > as for ssch.
> > >
> > > Signed-off-by: Cornelia Huck <address@hidden>
> > I had a look, and I don't have any new concerns.(New like not raised
> > before.)
> So, what was raised before that I did not address?
I had the cp->initialized in mind here. My understanding is that this is
the point at which safe accessors are necessary. But I consider that
I'm still not a fan of this try_lock() and -EAGAIN in write (and just
lock() in read approach), for the reasons I stated before. But it ain't
a deal-breaker for me. It is just that I don't get the benefit of the
busy looping userspace.