Re: [PATCH v2 3/7] vhost: Add kthread support in function vhost_workers_free()

[Stefano Garzarella]

On Tue, Oct 15, 2024 at 02:05:47PM +0800, Cindy Lu wrote:
> On Tue, 15 Oct 2024 at 05:06, Mike Christie <michael.christie@xxxxxxxxxx> wrote:
> > On 10/3/24 8:58 PM, Cindy Lu wrote:
> > > +static void vhost_workers_free(struct vhost_dev *dev)
> > > +{
> > > +     if (enforce_inherit_owner)
> > > +             vhost_workers_free_task(dev);
> > > +     else
> > > +             vhost_workers_free_kthread(dev);
> > > +}
> >
> > With patch 7, userspace could change enforce_inherit_owner after
> > we created thread and we would call the wrong function above.
> enforce_inherit_owner will only change before the owner was set.

As I pointed out in patch 7, enforce_inherit_owner seems to be shared 
among all vhost devices, so what happens if for example a user sets it 
to /dev/vhost-net, while /dev/vhost-vsock is already initialized and 
therefore already has an owner?

Thanks,
Stefano

> the process is like set enforce_inherit_owner---->set owner->
> thread/task creating
> in in patch 7's code I have add the check for vhost's owner, if the
> owner was set, the ioctl
> to set enforce_inherit_owner will fail
> Thanks
> Cindy