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arp_notify: allow drivers to explicitly request a notification event.

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Currently such notifications are only generated when the device comes up or the
address changes. However one use case for these notifications is to enable
faster network recovery after a virtual machine migration (by causing switches
to relearn their MAC tables). A migration appears to the network stack as a
temporary loss of carrier and therefore does not trigger either of the current
conditions. Rather than adding carrier up as a trigger (which can cause issues
when interfaces a flapping) simply add an interface which the driver can use
to explicitly trigger the notification.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Cc: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ian Campbell 2010-05-26 00:09:42 +00:00 committed by David S. Miller
parent 3f8dc2362f
commit 06c4648d46
4 changed files with 22 additions and 0 deletions
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2
include/linux/netdevice.h
View File

@ -1772,6 +1772,8 @@ extern void netif_carrier_on(struct net_device *dev);
extern void netif_carrier_off(struct net_device *dev);
extern void netif_notify_peers(struct net_device *dev);
/**
* netif_dormant_on - mark device as dormant.
* @dev: network device

1
include/linux/notifier.h
View File

@ -210,6 +210,7 @@ static inline int notifier_to_errno(int ret)
#define NETDEV_POST_INIT 0x0010
#define NETDEV_UNREGISTER_BATCH 0x0011
#define NETDEV_BONDING_DESLAVE 0x0012
#define NETDEV_NOTIFY_PEERS 0x0012
#define SYS_DOWN 0x0001 /* Notify of system down */
#define SYS_RESTART SYS_DOWN

1
net/ipv4/devinet.c
View File

@ -1081,6 +1081,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
}
ip_mc_up(in_dev);
/* fall through */
case NETDEV_NOTIFY_PEERS:
case NETDEV_CHANGEADDR:
/* Send gratuitous ARP to notify of link change */
if (IN_DEV_ARP_NOTIFY(in_dev)) {

18
net/sched/sch_generic.c
View File

@ -327,6 +327,24 @@ void netif_carrier_off(struct net_device *dev)
}
EXPORT_SYMBOL(netif_carrier_off);
/**
* netif_notify_peers - notify network peers about existence of @dev
* @dev: network device
*
* Generate traffic such that interested network peers are aware of
* @dev, such as by generating a gratuitous ARP. This may be used when
* a device wants to inform the rest of the network about some sort of
* reconfiguration such as a failover event or virtual machine
* migration.
*/
void netif_notify_peers(struct net_device *dev)
{
rtnl_lock();
call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
rtnl_unlock();
}
EXPORT_SYMBOL(netif_notify_peers);
/* "NOOP" scheduler: the best scheduler, recommended for all interfaces
under all circumstances. It is difficult to invent anything faster or
cheaper.