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: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -1030,6 +1030,21 @@ static inline bool inetdev_valid_mtu(unsigned mtu)
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return mtu >= 68;
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}
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static void inetdev_send_gratuitous_arp(struct net_device *dev,
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struct in_device *in_dev)
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{
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struct in_ifaddr *ifa = in_dev->ifa_list;
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if (!ifa)
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return;
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arp_send(ARPOP_REQUEST, ETH_P_ARP,
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ifa->ifa_address, dev,
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ifa->ifa_address, NULL,
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dev->dev_addr, NULL);
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}
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/* Called only under RTNL semaphore */
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static int inetdev_event(struct notifier_block *this, unsigned long event,
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@ -1082,18 +1097,13 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
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}
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ip_mc_up(in_dev);
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/* fall through */
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case NETDEV_NOTIFY_PEERS:
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case NETDEV_CHANGEADDR:
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if (!IN_DEV_ARP_NOTIFY(in_dev))
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break;
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/* fall through */
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case NETDEV_NOTIFY_PEERS:
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/* Send gratuitous ARP to notify of link change */
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if (IN_DEV_ARP_NOTIFY(in_dev)) {
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struct in_ifaddr *ifa = in_dev->ifa_list;
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if (ifa)
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arp_send(ARPOP_REQUEST, ETH_P_ARP,
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ifa->ifa_address, dev,
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ifa->ifa_address, NULL,
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dev->dev_addr, NULL);
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}
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inetdev_send_gratuitous_arp(dev, in_dev);
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break;
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case NETDEV_DOWN:
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ip_mc_down(in_dev);
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