netdev - Re: [PATCH 2/2] virtio-net: reduce the CPU consumption of dim worker

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Date: Fri, 22 Mar 2024 09:50:29 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: oe-kbuild@...ts.linux.dev, Heng Qi <hengqi@...ux.alibaba.com>,
	netdev@...r.kernel.org, virtualization@...ts.linux.dev,
	Jason Wang <jasowang@...hat.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev
Subject: Re: [PATCH 2/2] virtio-net: reduce the CPU consumption of dim worker

Hi Heng,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Heng-Qi/virtio-net-fix-possible-dim-status-unrecoverable/20240321-194759
base:   linus/master
patch link:    https://lore.kernel.org/r/1711021557-58116-3-git-send-email-hengqi%40linux.alibaba.com
patch subject: [PATCH 2/2] virtio-net: reduce the CPU consumption of dim worker
config: i386-randconfig-141-20240322 (https://download.01.org/0day-ci/archive/20240322/202403221133.J66oueZh-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

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@...el.com>
| Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
| Closes: https://lore.kernel.org/r/202403221133.J66oueZh-lkp@intel.com/

New smatch warnings:
drivers/net/virtio_net.c:5031 virtnet_probe() warn: missing error code 'err'

vim +/err +5031 drivers/net/virtio_net.c

986a4f4d452dec Jason Wang            2012-12-07  5006  	/* Allocate/initialize the rx/tx queues, and invoke find_vqs */
3f9c10b0d478a3 Amit Shah             2011-12-22  5007  	err = init_vqs(vi);
d2a7ddda9ffb1c Michael S. Tsirkin    2009-06-12  5008  	if (err)
d7dfc5cf56b0e3 Toshiaki Makita       2018-01-17  5009  		goto free;
296f96fcfc160e Rusty Russell         2007-10-22  5010  
3014a0d54820d2 Heng Qi               2023-10-08  5011  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
3014a0d54820d2 Heng Qi               2023-10-08  5012  		vi->intr_coal_rx.max_usecs = 0;
3014a0d54820d2 Heng Qi               2023-10-08  5013  		vi->intr_coal_tx.max_usecs = 0;
3014a0d54820d2 Heng Qi               2023-10-08  5014  		vi->intr_coal_rx.max_packets = 0;
3014a0d54820d2 Heng Qi               2023-10-08  5015  
3014a0d54820d2 Heng Qi               2023-10-08  5016  		/* Keep the default values of the coalescing parameters
3014a0d54820d2 Heng Qi               2023-10-08  5017  		 * aligned with the default napi_tx state.
3014a0d54820d2 Heng Qi               2023-10-08  5018  		 */
3014a0d54820d2 Heng Qi               2023-10-08  5019  		if (vi->sq[0].napi.weight)
3014a0d54820d2 Heng Qi               2023-10-08  5020  			vi->intr_coal_tx.max_packets = 1;
3014a0d54820d2 Heng Qi               2023-10-08  5021  		else
3014a0d54820d2 Heng Qi               2023-10-08  5022  			vi->intr_coal_tx.max_packets = 0;
3014a0d54820d2 Heng Qi               2023-10-08  5023  	}
3014a0d54820d2 Heng Qi               2023-10-08  5024  
d8cd72f1622753 Heng Qi               2024-03-21  5025  	INIT_LIST_HEAD(&vi->coal_list);
3014a0d54820d2 Heng Qi               2023-10-08  5026  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
d8cd72f1622753 Heng Qi               2024-03-21  5027  		vi->cvq_cmd_nums = 0;
d8cd72f1622753 Heng Qi               2024-03-21  5028  		vi->dim_loop_index = 0;
d8cd72f1622753 Heng Qi               2024-03-21  5029  
d8cd72f1622753 Heng Qi               2024-03-21  5030  		if (virtnet_init_coal_list(vi))
d8cd72f1622753 Heng Qi               2024-03-21 @5031  			goto free;

This should probably set the error code.

	err = virtnet_init_coal_list(vi);
	if (err)
		goto free;

d8cd72f1622753 Heng Qi               2024-03-21  5032  
3014a0d54820d2 Heng Qi               2023-10-08  5033  		/* The reason is the same as VIRTIO_NET_F_NOTF_COAL. */
d8cd72f1622753 Heng Qi               2024-03-21  5034  		for (i = 0; i < vi->max_queue_pairs; i++) {
d8cd72f1622753 Heng Qi               2024-03-21  5035  			vi->rq[i].packets_in_napi = 0;
3014a0d54820d2 Heng Qi               2023-10-08  5036  			if (vi->sq[i].napi.weight)
3014a0d54820d2 Heng Qi               2023-10-08  5037  				vi->sq[i].intr_coal.max_packets = 1;
3014a0d54820d2 Heng Qi               2023-10-08  5038  		}
d8cd72f1622753 Heng Qi               2024-03-21  5039  	}

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