Re: [PATCH 13/13] aio: remove aio_disable_external() API

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> Stefan Hajnoczi <stefanha@redhat.com> wrote:
> > All callers now pass is_external=false to aio_set_fd_handler() and
> > aio_set_event_notifier(). The aio_disable_external() API that
> > temporarily disables fd handlers that were registered is_external=true
> > is therefore dead code.
> >
> > Remove aio_disable_external(), aio_enable_external(), and the
> > is_external arguments to aio_set_fd_handler() and
> > aio_set_event_notifier().
> >
> > The entire test-fdmon-epoll test is removed because its sole purpose was
> > testing aio_disable_external().
> >
> > Parts of this patch were generated using the following coccinelle
> > (https://coccinelle.lip6.fr/) semantic patch:
> >
> >   @@
> >   expression ctx, fd, is_external, io_read, io_write, io_poll, io_poll_ready, opaque;
> >   @@
> >   - aio_set_fd_handler(ctx, fd, is_external, io_read, io_write, io_poll, io_poll_ready, opaque)
> >   + aio_set_fd_handler(ctx, fd, io_read, io_write, io_poll, io_poll_ready, opaque)
> >
> >   @@
> >   expression ctx, notifier, is_external, io_read, io_poll, io_poll_ready;
> >   @@
> >   - aio_set_event_notifier(ctx, notifier, is_external, io_read, io_poll, io_poll_ready)
> >   + aio_set_event_notifier(ctx, notifier, io_read, io_poll, io_poll_ready)
> >
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> 
> [....]
> 
> > diff --git a/migration/rdma.c b/migration/rdma.c
> > index df646be35e..aee41ca43e 100644
> > --- a/migration/rdma.c
> > +++ b/migration/rdma.c
> > @@ -3104,15 +3104,15 @@ static void qio_channel_rdma_set_aio_fd_handler(QIOChannel *ioc,
> >  {
> >      QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc);
> >      if (io_read) {
> > -        aio_set_fd_handler(ctx, rioc->rdmain->recv_comp_channel->fd,
> > -                           false, io_read, io_write, NULL, NULL, opaque);
> > -        aio_set_fd_handler(ctx, rioc->rdmain->send_comp_channel->fd,
> > -                           false, io_read, io_write, NULL, NULL, opaque);
> > +        aio_set_fd_handler(ctx, rioc->rdmain->recv_comp_channel->fd, io_read,
> > +                           io_write, NULL, NULL, opaque);
> > +        aio_set_fd_handler(ctx, rioc->rdmain->send_comp_channel->fd, io_read,
> > +                           io_write, NULL, NULL, opaque);
> >      } else {
> > -        aio_set_fd_handler(ctx, rioc->rdmaout->recv_comp_channel->fd,
> > -                           false, io_read, io_write, NULL, NULL, opaque);
> > -        aio_set_fd_handler(ctx, rioc->rdmaout->send_comp_channel->fd,
> > -                           false, io_read, io_write, NULL, NULL, opaque);
> > +        aio_set_fd_handler(ctx, rioc->rdmaout->recv_comp_channel->fd, io_read,
> > +                           io_write, NULL, NULL, opaque);
> > +        aio_set_fd_handler(ctx, rioc->rdmaout->send_comp_channel->fd, io_read,
> > +                           io_write, NULL, NULL, opaque);
> >      }
> >  }
> 
> Reviewed-by: Juan Quintela <quintela@redhat.com>
> 
> For the migration bits.
> I don't even want to know why the RDMA code uses a low level block layer API.

I don't think it's block specific.
It looks like it's because qio_channel uses aio in the case where
something QIO_CHANNEL_ERR_BLOCK and then waits for the recovery; see
4d9f675 that added it.

Dave
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK