On Thu, Jul 22, 2021 at 12:38:07AM +0200, Thomas Gleixner wrote:

That's fine because that's controlled by the driver consistently and it
(hopefully) makes sure that the admin queue is quiesced before
everything is torn down after the initial query.

Yes, it is.

The above can be fixed by adding an 'append' mode to the MSI code.

So IFF we get that append mode I think it would help to simplify
drivers that have unmanaged pre and post vectors, and/or do the above
proving.

So instead of currently requesting a single unmanaged vector, do
basic setup, tear it down, request N managed vectors with an unmanaged
pre-vector we could just keep the unmanaged vector, never tear it down
and just append the post vectors.  In the long run this could remove
the need to do the pre and post vectors entirely.