qdev: Add Error parameter to hide_device() callbacks

hide_device() is used for virtio-net failover, where the standby virtio
device delays creation of the primary device. It only makes sense to
have a single primary device for each standby device. Adding a second
one should result in an error instead of hiding it and never using it
afterwards.

Prepare for this by adding an Error parameter to the hide_device()
callback where virtio-net is informed about adding a primary device.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20211008133442.141332-12-kwolf@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 6 insertions, 3 deletions

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index d918b50a1d..c3a021c444 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -211,14 +211,17 @@ void device_listener_unregister(DeviceListener *listener)
     QTAILQ_REMOVE(&device_listeners, listener, link);
 }
 
-bool qdev_should_hide_device(QemuOpts *opts)
+bool qdev_should_hide_device(QemuOpts *opts, Error **errp)
 {
+    ERRP_GUARD();
     DeviceListener *listener;
 
     QTAILQ_FOREACH(listener, &device_listeners, link) {
         if (listener->hide_device) {
-            if (listener->hide_device(listener, opts)) {
+            if (listener->hide_device(listener, opts, errp)) {
                 return true;
+            } else if (*errp) {
+                return false;
             }
         }
     }
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index f205331dcf..a17d5739fc 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3304,7 +3304,7 @@ static void virtio_net_migration_state_notifier(Notifier *notifier, void *data)
 }
 
 static bool failover_hide_primary_device(DeviceListener *listener,
-                                         QemuOpts *device_opts)
+                                         QemuOpts *device_opts, Error **errp)
 {
     VirtIONet *n = container_of(listener, VirtIONet, primary_listener);
     const char *standby_id;