Re: [dpdk-dev] [PATCH v2 2/2] net/netvsc: support VF device hot add/remove

[Long Li <longli@microsoft.com>]

> Subject: Re: [dpdk-dev] [PATCH v2 2/2] net/netvsc: support VF device hot
> add/remove
> 
> On Mon, 21 Dec 2020 13:33:22 -0800
> Long Li <longli@linuxonhyperv.com> wrote:
> 
> > 	/* trying to get mac address if this is a network device*/
> > +		s = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
> > +		if (s == -1) {
> > +			PMD_DRV_LOG(ERR, "Failed to create socket
> errno %d\n",
> > +				    errno);
> > +			break;
> > +		}
> > +		strlcpy(req.ifr_name, dir->d_name, sizeof(req.ifr_name));
> > +		ret = ioctl(s, SIOCGIFHWADDR, &req);
> > +		close(s);
> > +		if (ret == -1) {
> > +			PMD_DRV_LOG(ERR, "Failed to send
> SIOCGIFHWADDR for "
> > +				    "device %s\n", dir->d_name);
> > +			break;
> > +		}
> > +		if (req.ifr_hwaddr.sa_family != ARPHRD_ETHER) {
> > +			closedir(di);
> > +			return;
> > +		}
> 
> You have sysfs directory open at this point, would it be easier to continue
> with sysfs to find the mac address?
> 
> 		snprintf(ifpath, sizeof(ifpath), "%s/address", dir->d_name);
> 		fd = openat(dirfd(di), ifpath, O_RDONLY);
> 		read(fd...)

I think sending SIOCGIFHWADDR through socket is safer. This is the same as vdev_netvsc does. If the network hardware is not ethernet, reading the address directly from sysfs may require some additional parsing.