Re: [dpdk-dev] [PATCH v5 1/3] kni: rework rte_kni_update_link using ioctl

On Thu, 26 Aug 2021 18:19:09 +0300
Igor Ryzhov [off-list ref] wrote:

 
+static int
+kni_ioctl_link(struct net *net, uint32_t ioctl_num,
+		unsigned long ioctl_param)
+{
+	struct kni_net *knet = net_generic(net, kni_net_id);
+	int ret = -EINVAL;
+	struct kni_dev *dev, *n;
+	struct rte_kni_link_info link_info;
+	struct net_device *netdev;
+
+	if (_IOC_SIZE(ioctl_num) > sizeof(link_info))
+		return -EINVAL;
+
+	if (copy_from_user(&link_info, (void *)ioctl_param, sizeof(link_info)))
+		return -EFAULT;
+
+	if (strlen(link_info.name) == 0)
+		return -EINVAL;
+
+	down_read(&knet->kni_list_lock);
+	list_for_each_entry_safe(dev, n, &knet->kni_list_head, list) {
+		if (strncmp(dev->name, link_info.name, RTE_KNI_NAMESIZE) != 0)
+			continue;
+
+		netdev = dev->net_dev;
+
+		if (link_info.status) {
+			netif_carrier_on(netdev);
+
+			dev->speed = link_info.speed;
+			dev->duplex = link_info.duplex;
+			dev->autoneg = link_info.autoneg;
+		} else {
+			netif_carrier_off(netdev);
+		}
+
+		ret = 0;
+		break;
+	}
+	up_read(&knet->kni_list_lock);
+
+	return ret;
+}
+

You need to be using the RTNL mutex in KNI here (and probably elsewhere).
The use of semaphore for list lock should also be replaced by a mutex.

The KNI driver was written long ago and was never reviewed by people
knowledgeable about kernel networking. That is one reason IMHO KNI
should not be used in production systems.