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Re: [PATCH 06/12] hw/xen: add get_frontend_path() method to XenDeviceClass
- To: David Woodhouse <dwmw2@xxxxxxxxxxxxx>, qemu-devel@xxxxxxxxxx
- From: Paul Durrant <xadimgnik@xxxxxxxxx>
- Date: Tue, 24 Oct 2023 13:59:07 +0100
- Cc: Kevin Wolf <kwolf@xxxxxxxxxx>, Hanna Reitz <hreitz@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Anthony Perard <anthony.perard@xxxxxxxxxx>, Marc-André Lureau <marcandre.lureau@xxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, "Michael S. Tsirkin" <mst@xxxxxxxxxx>, Marcel Apfelbaum <marcel.apfelbaum@xxxxxxxxx>, Richard Henderson <richard.henderson@xxxxxxxxxx>, Eduardo Habkost <eduardo@xxxxxxxxxxx>, Marcelo Tosatti <mtosatti@xxxxxxxxxx>, qemu-block@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx
- Delivery-date: Tue, 24 Oct 2023 12:59:17 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 24/10/2023 13:56, David Woodhouse wrote:
On Tue, 2023-10-24 at 13:42 +0100, Paul Durrant wrote:
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -711,8 +711,16 @@ static void xen_device_frontend_create(XenDevice *xendev,
Error **errp)
{
ERRP_GUARD();
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
+ XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);
- xendev->frontend_path = xen_device_get_frontend_path(xendev);
+ if (xendev_class->get_frontend_path) {
+ xendev->frontend_path = xendev_class->get_frontend_path(xendev, errp);
+ if (!xendev->frontend_path) {
+ return;
I think you need to update errp here to note that you are failing to
create the frontend.
If xendev_class->get_frontend_path returned NULL it will have filled in errp.
Ok, but a prepend to say that a lack of path there means we skip
frontend creation seems reasonable?
As a general rule (I'll be doing a bombing run on xen-bus once I get my
patch queue down into single digits) we should never check 'if (*errp)'
to check if a function had an error. It should *also* return a success
or failure indication, and we should cope with errp being NULL.
I'm pretty sure someone told me the exact opposite a few years back.
Paul
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