| Message ID | 20230302153435.1170111-19-dwmw2@infradead.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Enable PV backends with Xen/KVM emulation | expand |
On 02/03/2023 15:34, David Woodhouse wrote: > From: Paul Durrant <pdurrant@amazon.com> > > The xen-block code ends up calling aio_poll() through blkconf_geometry(), > which means we see watch events during the indirect call to > xendev_class->realize() in xen_device_realize(). Unfortunately this call > is made before populating the initial frontend and backend device nodes > in xenstore and hence xen_block_frontend_changed() (which is called from > a watch event) fails to read the frontend's 'state' node, and hence > believes the device is being torn down. This in-turn sets the backend > state to XenbusStateClosed and causes the device to be deleted before it > is fully set up, leading to the crash. > By simply moving the call to xendev_class->realize() after the initial > xenstore nodes are populated, this sorry state of affairs is avoided. > > Reported-by: David Woodhouse <dwmw@amazon.co.uk> > Signed-off-by: Paul Durrant <pdurrant@amazon.com> > Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> > --- > hw/xen/xen-bus.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > Reviewed-by: Paul Durrant <paul@xen.org>
diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index 9fe54967d4..c59850b1de 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -1034,13 +1034,6 @@ static void xen_device_realize(DeviceState *dev, Error **errp) goto unrealize; } - if (xendev_class->realize) { - xendev_class->realize(xendev, errp); - if (*errp) { - goto unrealize; - } - } - xen_device_backend_printf(xendev, "frontend", "%s", xendev->frontend_path); xen_device_backend_printf(xendev, "frontend-id", "%u", @@ -1059,6 +1052,13 @@ static void xen_device_realize(DeviceState *dev, Error **errp) xen_device_frontend_set_state(xendev, XenbusStateInitialising, true); } + if (xendev_class->realize) { + xendev_class->realize(xendev, errp); + if (*errp) { + goto unrealize; + } + } + xendev->exit.notify = xen_device_exit; qemu_add_exit_notifier(&xendev->exit); return;