Re: [RFC PATCH] vhost-vdpa: mark vhost device invalid to reflect vdpa device unregistration

[Jason Wang]

在 2021/7/5 上午11:48, Jason Wang 写道:
> 在 2021/7/5 上午4:52, gautam.dawar@xxxxxxxxxx 写道:
> >       vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> > @@ -1091,11 +1122,13 @@ static void vhost_vdpa_remove(struct 
> > vdpa_device *vdpa)
> >           opened = atomic_cmpxchg(&v->opened, 0, 1);
> >           if (!opened)
> >               break;
> > -        wait_for_completion_timeout(&v->completion,
> > -                        msecs_to_jiffies(1000));
> > -        dev_warn_once(&v->dev,
> > -                  "%s waiting for/dev/%s to be closed\n",
> > -                  __func__, dev_name(&v->dev));
> > +        if (!wait_for_completion_timeout(&v->completion,
> > +                        msecs_to_jiffies(1000))) {
> > +            dev_warn(&v->dev,
> > +                 "%s/dev/%s in use, continue..\n",
> > +                 __func__, dev_name(&v->dev));
> > +            break;
> > +        }
> >       } while (1);
> >         put_device(&v->dev);
> > +    v->dev_invalid = true;
>
>
> Besides the mapping handling mentioned by Michael. I think this can 
> lead use-after-free. put_device may release the memory.
>
> Another fundamental issue, vDPA is the parent of vhost-vDPA device. 
> I'm not sure the device core can allow the parent to go away first.


Or this probably means you need couple the fd loosely with the 
vhost-vDPA device.

Thanks


> Thanks