net: add ARP notify option for devices
Stephen Hemminger [Sun, 1 Feb 2009 09:04:33 +0000 (01:04 -0800)]
This adds another inet device option to enable gratuitous ARP
when device is brought up or address change. This is handy for
clusters or virtualization.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/ip-sysctl.txt
include/linux/inetdevice.h
include/linux/sysctl.h
kernel/sysctl_check.c
net/ipv4/devinet.c

index c771278..ff3f219 100644 (file)
@@ -782,6 +782,12 @@ arp_ignore - INTEGER
        The max value from conf/{all,interface}/arp_ignore is used
        when ARP request is received on the {interface}
 
+arp_notify - BOOLEAN
+       Define mode for notification of address and device changes.
+       0 - (default): do nothing
+       1 - Generate gratuitous arp replies when device is brought up
+           or hardware address changes.
+
 arp_accept - BOOLEAN
        Define behavior when gratuitous arp replies are received:
        0 - drop gratuitous arp frames
index 06fcdb4..acef2a7 100644 (file)
@@ -108,6 +108,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev)
 #define IN_DEV_ARPFILTER(in_dev)       IN_DEV_ORCONF((in_dev), ARPFILTER)
 #define IN_DEV_ARP_ANNOUNCE(in_dev)    IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE)
 #define IN_DEV_ARP_IGNORE(in_dev)      IN_DEV_MAXCONF((in_dev), ARP_IGNORE)
+#define IN_DEV_ARP_NOTIFY(in_dev)      IN_DEV_MAXCONF((in_dev), ARP_NOTIFY)
 
 struct in_ifaddr
 {
index 39d471d..e76d3b2 100644 (file)
@@ -490,6 +490,7 @@ enum
        NET_IPV4_CONF_ARP_IGNORE=19,
        NET_IPV4_CONF_PROMOTE_SECONDARIES=20,
        NET_IPV4_CONF_ARP_ACCEPT=21,
+       NET_IPV4_CONF_ARP_NOTIFY=22,
        __NET_IPV4_CONF_MAX
 };
 
index fafeb48..b38423c 100644 (file)
@@ -219,6 +219,7 @@ static const struct trans_ctl_table trans_net_ipv4_conf_vars_table[] = {
        { NET_IPV4_CONF_ARP_IGNORE,             "arp_ignore" },
        { NET_IPV4_CONF_PROMOTE_SECONDARIES,    "promote_secondaries" },
        { NET_IPV4_CONF_ARP_ACCEPT,             "arp_accept" },
+       { NET_IPV4_CONF_ARP_NOTIFY,             "arp_notify" },
        {}
 };
 
index 309997e..d519a6a 100644 (file)
@@ -1075,6 +1075,14 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
                        }
                }
                ip_mc_up(in_dev);
+               /* fall through */
+       case NETDEV_CHANGEADDR:
+               if (IN_DEV_ARP_NOTIFY(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);
@@ -1439,6 +1447,7 @@ static struct devinet_sysctl_table {
                DEVINET_SYSCTL_RW_ENTRY(ARP_ANNOUNCE, "arp_announce"),
                DEVINET_SYSCTL_RW_ENTRY(ARP_IGNORE, "arp_ignore"),
                DEVINET_SYSCTL_RW_ENTRY(ARP_ACCEPT, "arp_accept"),
+               DEVINET_SYSCTL_RW_ENTRY(ARP_NOTIFY, "arp_notify"),
 
                DEVINET_SYSCTL_FLUSHING_ENTRY(NOXFRM, "disable_xfrm"),
                DEVINET_SYSCTL_FLUSHING_ENTRY(NOPOLICY, "disable_policy"),