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Commit d11327ad authored by Ian Campbell's avatar Ian Campbell Committed by David S. Miller
Browse files

arp_notify: unconditionally send gratuitous ARP for NETDEV_NOTIFY_PEERS. 



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: default avatarIan Campbell <ian.campbell@citrix.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0550769b

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);