From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <shemminger@linux-foundation.org>
Subject: [RFC] Arp announce (for Xen)
Date: Thu, 1 Mar 2007 17:30:30 -0800
Message-ID: <20070301173030.754514ec@freekitty>
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	<20070301232529.648076372@goop.org>
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Cc: xen-devel@lists.xensource.com, Jeff Garzik <jeff@garzik.org>,
   Ian Pratt <ian.pratt@xensource.com>, netdev@vger.kernel.org,
   linux-kernel@vger.kernel.org, Chris Wright <chrisw@sous-sol.org>,
   Andi Kleen <ak@muc.de>, Zachary@smtp.osdl.org,
   virtualization@lists.osdl.org, Andrew Morton <akpm@linux-foundation.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
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What about implementing the unused arp_announce flag on the inetdevice?
Something like the following.  Totally untested...

Looks like it either was there (and got removed) or was planned but
never implemented.

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index e10794d..cefc339 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1089,6 +1089,16 @@ static int inetdev_event(struct notifier
 			}
 		}
 		ip_mc_up(in_dev);
+		/* fallthru */
+
+	case NETDEV_CHANGEADDR:
+		/* Send gratuitous ARP in case of address change or new device */
+		if (IN_DEV_ARP_ANNOUNCE(in_dev))
+			arp_send(ARPOP_REQUEST, ETH_P_ARP,
+				 in_dev->ifa_list->ifa_address, dev,
+				 in_dev->ifa_list->ifa_address, NULL, =

+				 dev->dev_addr, NULL);
+			=

 		break;
 	case NETDEV_DOWN:
 		ip_mc_down(in_dev);