Commit 485e3ce8 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Stefan Hajnoczi
Browse files

dataplane: fix hang introduced by AioContext transition 



The bug is that the EventNotifiers do have a NULL io_flush callback.
Because _none_ of the callbacks on the dataplane AioContext have such a
callback, aio_poll will simply do nothing.  Fixed by adding the callbacks:
the ioeventfd will always be polled (this can change in the future to
pause/resume the processing during live snapshots or similar operations);
the ioqueue will be polled if there are outstanding requests.

I must admit I have screwed up my testing somehow, because commit
2c20e711 does not work even if cherry-picked on top of 1.4.0, and this
patch fixes it there as well.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 28f08246

hw/dataplane/virtio-blk.c

+15 −2
Original line number Diff line number Diff line
@@ -263,6 +263,11 @@ static int process_request(IOQueue *ioq, struct iovec iov[], 
    }

}



static int flush_true(EventNotifier *e)

{

    return true;

}



static void handle_notify(EventNotifier *e)

{

    VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
@@ -342,6 +347,14 @@ static void handle_notify(EventNotifier *e) 
    }

}



static int flush_io(EventNotifier *e)

{

    VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,

                                           io_notifier);



    return s->num_reqs > 0;

}



static void handle_io(EventNotifier *e)

{

    VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
@@ -472,7 +485,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) 
        exit(1);

    }

    s->host_notifier = *virtio_queue_get_host_notifier(vq);

    aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify, NULL);

    aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify, flush_true);



    /* Set up ioqueue */

    ioq_init(&s->ioqueue, s->fd, REQ_MAX);
@@ -480,7 +493,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) 
        ioq_put_iocb(&s->ioqueue, &s->requests[i].iocb);

    }

    s->io_notifier = *ioq_get_notifier(&s->ioqueue);

    aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io, NULL);

    aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io, flush_io);



    s->started = true;

    trace_virtio_blk_data_plane_start(s);