[PATCH net v3] virtio-net: fix recursived rtnl_lock() during probe()

[PATCH net v3] virtio-net: fix recursived rtnl_lock() during probe()

[Zigit Zo]

The deadlock appears in a stack trace like:

  virtnet_probe()
    rtnl_lock()
    virtio_config_changed_work()
      netdev_notify_peers()
        rtnl_lock()

It happens if the VMM sends a VIRTIO_NET_S_ANNOUNCE request while the
virtio-net driver is still probing.

The config_work in probe() will get scheduled until virtnet_open() enables
the config change notification via virtio_config_driver_enable().

Fixes: df28de7b0050 ("virtio-net: synchronize operstate with admin state on up/down")
Signed-off-by: Zigit Zo <zuozhijie@bytedance.com>
---
v3 -> v2:
* Simplify the changes.
v1 -> v2:
* Check vi->status in virtnet_open().
* https://lore.kernel.org/netdev/20250702103722.576219-1-zuozhijie@bytedance.com/
v1:
* https://lore.kernel.org/netdev/20250630095109.214013-1-zuozhijie@bytedance.com/
---
 drivers/net/virtio_net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 5d674eb9a0f2..82b4a2a2b8c4 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -7059,7 +7059,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 	   otherwise get link status from config. */
 	netif_carrier_off(dev);
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
-		virtnet_config_changed_work(&vi->config_work);
+		virtio_config_changed(vi->vdev);
 	} else {
 		vi->status = VIRTIO_NET_S_LINK_UP;
 		virtnet_update_settings(vi);

base-commit: dae7f9cbd1909de2b0bccc30afef95c23f93e477
-- 
2.49.0

Re: [PATCH net v3] virtio-net: fix recursived rtnl_lock() during probe()

[Michael S. Tsirkin]

On Wed, Jul 16, 2025 at 07:57:17PM +0800, Zigit Zo wrote:
> The deadlock appears in a stack trace like:
> 
>   virtnet_probe()
>     rtnl_lock()
>     virtio_config_changed_work()
>       netdev_notify_peers()
>         rtnl_lock()
> 
> It happens if the VMM sends a VIRTIO_NET_S_ANNOUNCE request while the
> virtio-net driver is still probing.
> 
> The config_work in probe() will get scheduled until virtnet_open() enables
> the config change notification via virtio_config_driver_enable().
> 
> Fixes: df28de7b0050 ("virtio-net: synchronize operstate with admin state on up/down")
> Signed-off-by: Zigit Zo <zuozhijie@bytedance.com>

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

> ---
> v3 -> v2:
> * Simplify the changes.
> v1 -> v2:
> * Check vi->status in virtnet_open().
> * https://lore.kernel.org/netdev/20250702103722.576219-1-zuozhijie@bytedance.com/
> v1:
> * https://lore.kernel.org/netdev/20250630095109.214013-1-zuozhijie@bytedance.com/
> ---
>  drivers/net/virtio_net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 5d674eb9a0f2..82b4a2a2b8c4 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -7059,7 +7059,7 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	   otherwise get link status from config. */
>  	netif_carrier_off(dev);
>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
> -		virtnet_config_changed_work(&vi->config_work);
> +		virtio_config_changed(vi->vdev);
>  	} else {
>  		vi->status = VIRTIO_NET_S_LINK_UP;
>  		virtnet_update_settings(vi);
> 
> base-commit: dae7f9cbd1909de2b0bccc30afef95c23f93e477
> -- 
> 2.49.0

Re: [PATCH net v3] virtio-net: fix recursived rtnl_lock() during probe()

[Jason Wang]

On Wed, Jul 16, 2025 at 7:57 PM Zigit Zo <zuozhijie@bytedance.com> wrote:
>
> The deadlock appears in a stack trace like:
>
>   virtnet_probe()
>     rtnl_lock()
>     virtio_config_changed_work()
>       netdev_notify_peers()
>         rtnl_lock()
>
> It happens if the VMM sends a VIRTIO_NET_S_ANNOUNCE request while the
> virtio-net driver is still probing.
>
> The config_work in probe() will get scheduled until virtnet_open() enables
> the config change notification via virtio_config_driver_enable().
>
> Fixes: df28de7b0050 ("virtio-net: synchronize operstate with admin state on up/down")
> Signed-off-by: Zigit Zo <zuozhijie@bytedance.com>
> ---

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks

Re: [PATCH net v3] virtio-net: fix recursived rtnl_lock() during probe()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 16 Jul 2025 19:57:17 +0800 you wrote:
> The deadlock appears in a stack trace like:
> 
>   virtnet_probe()
>     rtnl_lock()
>     virtio_config_changed_work()
>       netdev_notify_peers()
>         rtnl_lock()
> 
> [...]

Here is the summary with links:
  - [net,v3] virtio-net: fix recursived rtnl_lock() during probe()
    https://git.kernel.org/netdev/net/c/be5dcaed694e

You are awesome, thank you!
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