arp_notify: unconditionally send gratuitous ARP for NETDEV_NOTIFY_PEERS. (d11327ad) · Commits · 戴 / test

NETDEV_NOTIFY_PEER is an explicit request by the driver to send a link notification while NETDEV_UP/NETDEV_CHANGEADDR generate link notifications as a sort of side effect. In the later cases the sysctl option is present because link notification events can have undesired effects e.g. if the link is flapping. I don't think this applies in the case of an explicit request from a driver. This patch makes NETDEV_NOTIFY_PEER unconditional, if preferred we could add a new sysctl for this case which defaults to on. This change causes Xen post-migration ARP notifications (which cause switches to relearn their MAC tables etc) to be sent by default. Signed-off-by:

Ian Campbell <ian.campbell@citrix.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/ipv4/devinet.c

+20 −10

Original line number	Diff line number	Diff line
		@@ -1030,6 +1030,21 @@ static inline bool inetdev_valid_mtu(unsigned mtu)
		return mtu >= 68;
		}

		static void inetdev_send_gratuitous_arp(struct net_device *dev,
		struct in_device *in_dev)

		{
		struct in_ifaddr *ifa = in_dev->ifa_list;

		if (!ifa)
		return;

		arp_send(ARPOP_REQUEST, ETH_P_ARP,
		ifa->ifa_address, dev,
		ifa->ifa_address, NULL,
		dev->dev_addr, NULL);
		}

		/* Called only under RTNL semaphore */

		static int inetdev_event(struct notifier_block *this, unsigned long event,
		@@ -1082,18 +1097,13 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
		}
		ip_mc_up(in_dev);
		/* fall through */
		case NETDEV_NOTIFY_PEERS:
		case NETDEV_CHANGEADDR:
		if (!IN_DEV_ARP_NOTIFY(in_dev))
		break;
		/* fall through */
		case NETDEV_NOTIFY_PEERS:
		/* Send gratuitous ARP to notify of link change */
		if (IN_DEV_ARP_NOTIFY(in_dev)) {
		struct in_ifaddr *ifa = in_dev->ifa_list;

		if (ifa)
		arp_send(ARPOP_REQUEST, ETH_P_ARP,
		ifa->ifa_address, dev,
		ifa->ifa_address, NULL,
		dev->dev_addr, NULL);
		}
		inetdev_send_gratuitous_arp(dev, in_dev);
		break;
		case NETDEV_DOWN:
		ip_mc_down(in_dev);

Admin message