Ian Pratt wrote:
Whilst I might agree that from a purist point of view having netfront do
this is a violation of layering, it's already accepted in some other
upstream drivers
It's pretty clear it's not going to be accepted in the netfront that goes into
upstream Linux, at least not without sedating various LKML folk first :)
Stephen Hemminger posted a patch to add this capability generically so
it wouldn't be a netfront-specific piece of behaviour. I have not
submitted it for upstream yet, mainly because nobody has
confirmed/tested that it really does what we need. But it looks
reasonable, and it should be accepted once we confirm its correct.
J
Subject: ARP notify option
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.
Tested on a normal device (not Xen).
Signed-off-by: Stephen Hemminger <shemminge@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/networking/ip-sysctl.txt | 6 ++++++
include/linux/inetdevice.h | 2 ++
include/linux/sysctl.h | 1 +
net/ipv4/devinet.c | 16 ++++++++++++++++
4 files changed, 25 insertions(+)
===================================================================
--- net-2.6.22.orig/Documentation/networking/ip-sysctl.txt
+++ net-2.6.22/Documentation/networking/ip-sysctl.txt
@@ -732,6 +732,12 @@
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
===================================================================
--- net-2.6.22.orig/include/linux/inetdevice.h
+++ net-2.6.22/include/linux/inetdevice.h
@@ -26,6 +26,7 @@
int arp_announce;
int arp_ignore;
int arp_accept;
+ int arp_notify;
int medium_id;
int no_xfrm;
int no_policy;
@@ -84,6 +85,7 @@
#define IN_DEV_ARPFILTER(in_dev) (ipv4_devconf.arp_filter ||
(in_dev)->cnf.arp_filter)
#define IN_DEV_ARP_ANNOUNCE(in_dev) (max(ipv4_devconf.arp_announce,
(in_dev)->cnf.arp_announce))
#define IN_DEV_ARP_IGNORE(in_dev) (max(ipv4_devconf.arp_ignore,
(in_dev)->cnf.arp_ignore))
+#define IN_DEV_ARP_NOTIFY(in_dev) (ipv4_devconf.arp_notify ||
(in_dev)->cnf.arp_notify)
struct in_ifaddr
{
===================================================================
--- net-2.6.22.orig/include/linux/sysctl.h
+++ net-2.6.22/include/linux/sysctl.h
@@ -495,6 +495,7 @@
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
};
===================================================================
--- net-2.6.22.orig/net/ipv4/devinet.c
+++ net-2.6.22/net/ipv4/devinet.c
@@ -1089,6 +1089,14 @@
}
}
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);
@@ -1495,6 +1503,14 @@
.proc_handler = &proc_dointvec,
},
{
+ .ctl_name = NET_IPV4_CONF_ARP_NOTIFY,
+ .procname = "arp_notify",
+ .data = &ipv4_devconf.arp_notify,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
.ctl_name = NET_IPV4_CONF_NOXFRM,
.procname = "disable_xfrm",
.data = &ipv4_devconf.no_xfrm,
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