Re: [PATCH v4 02/17] x86/acrn: Introduce acrn_{setup, remove}_intr_handler()

[Shuo A Liu]

Hi Boris,

On Tue 29.Sep'20 at 22:26:54 +0200, Borislav Petkov wrote:
> On Tue, Sep 29, 2020 at 10:07:17PM +0200, Thomas Gleixner wrote:
> > That does not prevent that either and notifiers suck.
>
> Bah, atomic notifiers run functions which cannot block, not what is
> needed here, right.
>
> > The pointer is fine and if something removes the handler before all of
> > the muck is shutdown then the author can keep the pieces and mop up
> > the remains.
>
> Uhu, so what makes sure that the module is not removed while an IRQ is
> happening?

The precondition of the removing of the module is that there is no
User VM living (every opening of the dev file will hold a ref count of
the module). The interrupt only can occur with active User VMs. So if
a notification interrupt is happending, the module cannot be removed as
there is still User VM living.

Thanks
shuo