Re: [PATCH v2 16/16] virtio: make it possible to detach host notifier from any thread

[Stefan Hajnoczi]

On Wed, 19 Apr 2023 at 14:52, Eric Blake <eblake@redhat.com> wrote:
>
> On Wed, Apr 19, 2023 at 01:28:17PM -0400, Stefan Hajnoczi wrote:
> > virtio_queue_aio_detach_host_notifier() does two things:
> > 1. It removes the fd handler from the event loop.
> > 2. It processes the virtqueue one last time.
> >
> > The first step can be peformed by any thread and without taking the
> > AioContext lock.
> >
> > The second step may need the AioContext lock (depending on the device
> > implementation) and runs in the thread where request processing takes
> > place. virtio-blk and virtio-scsi therefore call
> > virtio_queue_aio_detach_host_notifier() from a BH that is scheduled in
> > AioContext
> >
> > Scheduling a BH is undesirable for .drained_begin() functions. The next
> > patch will introduce a .drained_begin() function that needs to call
> > virtio_queue_aio_detach_host_notifier().
> >
> > Move the virtqueue processing out to the callers of
> > virtio_queue_aio_detach_host_notifier() so that the function can be
> > called from any thread. This is in preparation for the next patch.
> >
>
> This mentions a next patch, but is 16/16 in the series.  Am I missing
> something?

Good thing you caught this. The patch series was truncated because I
was in the middle of git rebase -i :(.

I will send a v3 with the remaining patches.

Thanks,
Stefan