Re: [PATCH v2 1/6] hw/xen: Set XenBackendInstance in the XenDevice before realizing it

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

On Wed, 2023-11-22 at 22:56 +0000, Volodymyr Babchuk wrote:
> 
> 
> Paul Durrant <xadimgnik@xxxxxxxxx> writes:
> 
> > On 21/11/2023 22:10, Volodymyr Babchuk wrote:
> > > From: David Woodhouse <dwmw@xxxxxxxxxxxx>
> > > This allows a XenDevice implementation to know whether it was
> > > created
> > > by QEMU, or merely discovered in XenStore after the toolstack created
> > > it. This will allow us to create frontend/backend nodes only when we
> > > should, rather than unconditionally attempting to overwrite them from
> > > a driver domain which doesn't have privileges to do so.
> > > As an added benefit, it also means we no longer have to call the
> > > xen_backend_set_device() function from the device models immediately
> > > after calling qdev_realize_and_unref(). Even though we could make
> > > the argument that it's safe to do so, and the pointer to the unreffed
> > > device *will* actually still be valid, it still made my skin itch to
> > > look at it.
> > > Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> > > ---
> > >   hw/block/xen-block.c         | 3 +--
> > >   hw/char/xen_console.c        | 2 +-
> > >   hw/net/xen_nic.c             | 2 +-
> > >   hw/xen/xen-bus.c             | 4 ++++
> > >   include/hw/xen/xen-backend.h | 2 --
> > >   include/hw/xen/xen-bus.h     | 2 ++
> > >   6 files changed, 9 insertions(+), 6 deletions(-)
> > > 
> > 
> > Actually, I think you should probably update
> > xen_backend_try_device_destroy() in this patch too. It currently uses
> > xen_backend_list_find() to check whether the specified XenDevice has
> > an associated XenBackendInstance.
> 
> Sure. Looks like it is the only user of xen_backend_list_find(), so we
> can get rid of it as well.
> 
> I'll drop your R-b tag, because of those additional changes in the new
> version.

I think it's fine to keep. He told me to do it :)

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