Re: [PATCH v5 4/8] vfio: Wait for dma-buf invalidation to complete

[Jason Gunthorpe]

On Fri, Jan 30, 2026 at 02:21:08PM +0100, Christian König wrote:

> That would work for me.
> 
> Question is if you really want to do it this way? See usually
> exporters try to avoid blocking such functions.

Yes, it has to be this way, revoke is a synchronous user space
triggered operation around things like FLR or device close. We can't
defer it into some background operation like pm.

> >>>  		}
> >>>  		fput(priv->dmabuf->file);
> >>
> >> This is also extremely questionable. Why doesn't the dmabuf have
> >> a reference while on the linked list?

If we hold a refcount while on the list then the FD can never be
closed.

There is locking protecting the list so that it is safe and close
continues to work right.

Jason