Re: [PATCH net] virtio-net: fix a rtnl_lock() deadlock during probing

[kernel test robot <lkp@intel.com>]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20250630095109.214013-1-zuozhijie@bytedance.com>
References: <20250630095109.214013-1-zuozhijie@bytedance.com>
TO: Zigit Zo <zuozhijie@bytedance.com>
TO: mst@redhat.com
TO: jasowang@redhat.com
TO: xuanzhuo@linux.alibaba.com
TO: eperezma@redhat.com
CC: zuozhijie@bytedance.com
CC: virtualization@lists.linux.dev
CC: netdev@vger.kernel.org
CC: linux-kernel@vger.kernel.org

Hi Zigit,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 2def09ead4ad5907988b655d1e1454003aaf8297]

url:    https://github.com/intel-lab-lkp/linux/commits/Zigit-Zo/virtio-net-fix-a-rtnl_lock-deadlock-during-probing/20250630-175257
base:   2def09ead4ad5907988b655d1e1454003aaf8297
patch link:    https://lore.kernel.org/r/20250630095109.214013-1-zuozhijie%40bytedance.com
patch subject: [PATCH net] virtio-net: fix a rtnl_lock() deadlock during probing
:::::: branch date: 32 hours ago
:::::: commit date: 32 hours ago
config: x86_64-randconfig-161-20250701 (https://download.01.org/0day-ci/archive/20250702/202507020158.2hoKFZXE-lkp@intel.com/config)
compiler: clang version 20.1.7 (https://github.com/llvm/llvm-project 6146a88f60492b520a36f8f8f3231e15f3cc6082)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202507020158.2hoKFZXE-lkp@intel.com/

New smatch warnings:
drivers/net/virtio_net.c:6221 __virtnet_config_changed_work() error: uninitialized symbol 'virtio_cread_v'.
drivers/net/virtio_net.c:6225 __virtnet_config_changed_work() error: uninitialized symbol 'v'.

Old smatch warnings:
drivers/net/virtio_net.c:2108 build_skb_from_xdp_buff() error: uninitialized symbol 'nr_frags'.
drivers/net/virtio_net.c:2190 virtnet_build_xdp_buff_mrg() error: uninitialized symbol 'shinfo'.
drivers/net/virtio_net.c:3122 virtnet_update_settings() error: uninitialized symbol 'virtio_cread_v'.

vim +/virtio_cread_v +6221 drivers/net/virtio_net.c

76288b4e573e06 Stephen Hemminger  2009-01-06  6213  
d72ba54248be27 Zigit Zo           2025-06-30  6214  static void __virtnet_config_changed_work(struct work_struct *work,
d72ba54248be27 Zigit Zo           2025-06-30  6215  					  bool check_announce)
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6216  {
586d17c5a01bf1 Jason Wang         2012-04-11  6217  	struct virtnet_info *vi =
586d17c5a01bf1 Jason Wang         2012-04-11  6218  		container_of(work, struct virtnet_info, config_work);
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6219  	u16 v;
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6220  
855e0c5288177b Rusty Russell      2013-10-14 @6221  	if (virtio_cread_feature(vi->vdev, VIRTIO_NET_F_STATUS,
855e0c5288177b Rusty Russell      2013-10-14  6222  				 struct virtio_net_config, status, &v) < 0)
507613bf31f4bc Michael S. Tsirkin 2014-10-15  6223  		return;
586d17c5a01bf1 Jason Wang         2012-04-11  6224  
d72ba54248be27 Zigit Zo           2025-06-30 @6225  	if (check_announce && (v & VIRTIO_NET_S_ANNOUNCE)) {
ee89bab14e8576 Amerigo Wang       2012-08-09  6226  		netdev_notify_peers(vi->dev);
586d17c5a01bf1 Jason Wang         2012-04-11  6227  		virtnet_ack_link_announce(vi);
586d17c5a01bf1 Jason Wang         2012-04-11  6228  	}
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6229  
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6230  	/* Ignore unknown (future) status bits */
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6231  	v &= VIRTIO_NET_S_LINK_UP;
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6232  
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6233  	if (vi->status == v)
507613bf31f4bc Michael S. Tsirkin 2014-10-15  6234  		return;
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6235  
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6236  	vi->status = v;
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6237  
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6238  	if (vi->status & VIRTIO_NET_S_LINK_UP) {
faa9b39f0e9ddf Jason Baron        2018-01-05  6239  		virtnet_update_settings(vi);
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6240  		netif_carrier_on(vi->dev);
986a4f4d452dec Jason Wang         2012-12-07  6241  		netif_tx_wake_all_queues(vi->dev);
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6242  	} else {
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6243  		netif_carrier_off(vi->dev);
986a4f4d452dec Jason Wang         2012-12-07  6244  		netif_tx_stop_all_queues(vi->dev);
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6245  	}
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6246  }
9f4d26d0f3016c Mark McLoughlin    2009-01-19  6247  

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