Make sure we don't pass NULL to qdev_set_parent_bus(). Also simplify
code a bit and fix a typo.
This fixes CID 1407224.

Fixes: 9711cd0dfc3f ("net/virtio: add failover support")
Signed-off-by: Jens Freimann <jfreimann@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..78f1e4e87c 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

On Wed, Nov 20, 2019 at 03:38:58PM +0100, Jens Freimann wrote:
> Make sure we don't pass NULL to qdev_set_parent_bus(). Also simplify
> code a bit and fix a typo.
> This fixes CID 1407224.
> 
> Fixes: 9711cd0dfc3f ("net/virtio: add failover support")
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>

patch itself is ok I think

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

but some questions on the commit log

> ---
>  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..78f1e4e87c 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,

So the logic actually was inverted here? Then ... how did this work?
and how was it tested?
Also, pls mention the change in the commit log.

> @@ -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

On Wed, Nov 20, 2019 at 10:04:01AM -0500, Michael S. Tsirkin wrote:
>On Wed, Nov 20, 2019 at 03:38:58PM +0100, Jens Freimann wrote:
>> Make sure we don't pass NULL to qdev_set_parent_bus(). Also simplify
>> code a bit and fix a typo.
>> This fixes CID 1407224.
>>
>> Fixes: 9711cd0dfc3f ("net/virtio: add failover support")
>> Signed-off-by: Jens Freimann <jfreimann@redhat.com>
>
>patch itself is ok I think
>
>Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
>
>but some questions on the commit log
>
>> ---
>>  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..78f1e4e87c 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,
>
>So the logic actually was inverted here? Then ... how did this work?
>and how was it tested?

It did not work and I missed the error in my test output. I tested it
now manually by migrating and then cancelling. Device was added back
to source VM successfully.

Will sent new version with better patch description.

Thanks!

regards
Jens