| From | Andi Kleen <> | Subject | [PATCH] [171/275] arp_notify: unconditionally send gratuitous ARP for NETDEV_NOTIFY_PEERS. | Date | Wed, 30 Mar 2011 14:06:53 -0700 (PDT) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Ian Campbell <Ian.Campbell@citrix.com>
commit d11327ad6695db8117c78d70611e71102ceec2ac upstream.
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> Signed-off-by: Andi Kleen <ak@linux.intel.com> [reported to solve hyperv live migration problem - gkh] Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Mike Surcouf <mike@surcouf.co.uk> Cc: Hank Janssen <hjanssen@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- net/ipv4/devinet.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)
Index: linux-2.6.35.y/net/ipv4/devinet.c =================================================================== --- linux-2.6.35.y.orig/net/ipv4/devinet.c 2011-03-29 22:50:55.819830128 -0700 +++ linux-2.6.35.y/net/ipv4/devinet.c 2011-03-29 23:03:01.802254055 -0700 @@ -1029,6 +1029,21 @@ 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, @@ -1081,18 +1096,13 @@ } 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);
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