[PATCH v3 3/4] net/virtio: fix re-plugging of primary device

[Jens Freimann <jfreimann@redhat.com>]

failover_replug_primary was returning true on failure which lead to
re-plug not working when a migration failed.  Fix this by returning
success when hotplug worked.  This is a bug that was missed in last
round of testing but was tested succesfully with this version.  Also
make sure we don't pass NULL to qdev_set_parent_bus().

This fixes CID 1407224.

Fixes: 9711cd0dfc3f ("net/virtio: add failover support")
Signed-off-by: Jens Freimann <jfreimann@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/net/virtio-net.c | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index ac4d19109e..565dea0b93 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -2805,25 +2805,33 @@ static bool failover_replug_primary(VirtIONet *n, Error **errp)
         n->primary_device_opts = qemu_opts_from_qdict(
                 qemu_find_opts("device"),
                 n->primary_device_dict, errp);
-    }
-    if (n->primary_device_opts) {
-        if (n->primary_dev) {
-            n->primary_bus = n->primary_dev->parent_bus;
-        }
-        qdev_set_parent_bus(n->primary_dev, n->primary_bus);
-        n->primary_should_be_hidden = false;
-        qemu_opt_set_bool(n->primary_device_opts,
-                "partially_hotplugged", true, errp);
-        hotplug_ctrl = qdev_get_hotplug_handler(n->primary_dev);
-        if (hotplug_ctrl) {
-            hotplug_handler_pre_plug(hotplug_ctrl, n->primary_dev, errp);
-            hotplug_handler_plug(hotplug_ctrl, n->primary_dev, errp);
+        if (!n->primary_device_opts) {
+            error_setg(errp, "virtio_net: couldn't find primary device opts");
+            goto out;
         }
-        if (!n->primary_dev) {
+    }
+    if (!n->primary_dev) {
             error_setg(errp, "virtio_net: couldn't find primary device");
-        }
+            goto out;
     }
-    return *errp != NULL;
+
+    n->primary_bus = n->primary_dev->parent_bus;
+    if (!n->primary_bus) {
+        error_setg(errp, "virtio_net: couldn't find primary bus");
+        goto out;
+    }
+    qdev_set_parent_bus(n->primary_dev, n->primary_bus);
+    n->primary_should_be_hidden = false;
+    qemu_opt_set_bool(n->primary_device_opts,
+                      "partially_hotplugged", true, errp);
+    hotplug_ctrl = qdev_get_hotplug_handler(n->primary_dev);
+    if (hotplug_ctrl) {
+        hotplug_handler_pre_plug(hotplug_ctrl, n->primary_dev, errp);
+        hotplug_handler_plug(hotplug_ctrl, n->primary_dev, errp);
+    }
+
+out:
+    return *errp == NULL;
 }
 
 static void virtio_net_handle_migration_primary(VirtIONet *n,
@@ -2852,7 +2860,7 @@ static void virtio_net_handle_migration_primary(VirtIONet *n,
             warn_report("couldn't unplug primary device");
         }
     } else if (migration_has_failed(s)) {
-        /* We already unplugged the device let's plugged it back */
+        /* We already unplugged the device let's plug it back */
         if (!failover_replug_primary(n, &err)) {
             if (err) {
                 error_report_err(err);
-- 
2.21.0