Re: [PATCH net-next v3 4/4] virtio_net: improve dim command request efficiency

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

Hi Heng,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Heng-Qi/virtio_net-passing-control_buf-explicitly/20240606-141748
base:   net-next/main
patch link:    https://lore.kernel.org/r/20240606061446.127802-5-hengqi%40linux.alibaba.com
patch subject: [PATCH net-next v3 4/4] virtio_net: improve dim command request efficiency
config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20240607/202406070616.vNSLJTt2-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240607/202406070616.vNSLJTt2-lkp@intel.com/reproduce)

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202406070616.vNSLJTt2-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/net/virtio_net.c: In function 'virtnet_get_cvq_work':
>> drivers/net/virtio_net.c:2841:20: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
    2841 |                 if (wait_coal)
         |                    ^


vim +/else +2841 drivers/net/virtio_net.c

  2813	
  2814	static void virtnet_get_cvq_work(struct work_struct *work)
  2815	{
  2816		struct virtnet_info *vi =
  2817			container_of(work, struct virtnet_info, get_cvq);
  2818		struct virtnet_coal_node *wait_coal;
  2819		bool valid = false;
  2820		unsigned int tmp;
  2821		void *res;
  2822	
  2823		mutex_lock(&vi->cvq_lock);
  2824		while ((res = virtqueue_get_buf(vi->cvq, &tmp)) != NULL) {
  2825			complete((struct completion *)res);
  2826			valid = true;
  2827		}
  2828		mutex_unlock(&vi->cvq_lock);
  2829	
  2830		if (!valid)
  2831			return;
  2832	
  2833		while (true) {
  2834			wait_coal = NULL;
  2835			mutex_lock(&vi->coal_wait_lock);
  2836			if (!list_empty(&vi->coal_wait_list))
  2837				wait_coal = list_first_entry(&vi->coal_wait_list,
  2838							     struct virtnet_coal_node,
  2839							     list);
  2840			mutex_unlock(&vi->coal_wait_lock);
> 2841			if (wait_coal)
  2842				if (virtnet_add_dim_command(vi, wait_coal))
  2843					break;
  2844			else
  2845				break;
  2846		}
  2847	}
  2848	static int virtnet_set_mac_address(struct net_device *dev, void *p)
  2849	{
  2850		struct virtnet_info *vi = netdev_priv(dev);
  2851		struct virtio_device *vdev = vi->vdev;
  2852		int ret;
  2853		struct sockaddr *addr;
  2854		struct scatterlist sg;
  2855	
  2856		if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STANDBY))
  2857			return -EOPNOTSUPP;
  2858	
  2859		addr = kmemdup(p, sizeof(*addr), GFP_KERNEL);
  2860		if (!addr)
  2861			return -ENOMEM;
  2862	
  2863		ret = eth_prepare_mac_addr_change(dev, addr);
  2864		if (ret)
  2865			goto out;
  2866	
  2867		if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
  2868			sg_init_one(&sg, addr->sa_data, dev->addr_len);
  2869			if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
  2870						  VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
  2871				dev_warn(&vdev->dev,
  2872					 "Failed to set mac address by vq command.\n");
  2873				ret = -EINVAL;
  2874				goto out;
  2875			}
  2876		} else if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC) &&
  2877			   !virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
  2878			unsigned int i;
  2879	
  2880			/* Naturally, this has an atomicity problem. */
  2881			for (i = 0; i < dev->addr_len; i++)
  2882				virtio_cwrite8(vdev,
  2883					       offsetof(struct virtio_net_config, mac) +
  2884					       i, addr->sa_data[i]);
  2885		}
  2886	
  2887		eth_commit_mac_addr_change(dev, p);
  2888		ret = 0;
  2889	
  2890	out:
  2891		kfree(addr);
  2892		return ret;
  2893	}
  2894	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki