Re: arp_notify: allow drivers to explicitly request a notification event.

[Greg KH <greg@kroah.com>]

Wait, Ian, are you sure this patch is correct?  Look below in
notifier.h:

On Wed, May 26, 2010 at 12:09:42AM +0000, Ian Campbell wrote:
> From: Ian Campbell <Ian.Campbell@citrix.com>
> 
> commit 06c4648d46d1b757d6b9591a86810be79818b60c upstream.
> 
> 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
> Signed-off-by: David S. Miller <davem@davemloft.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> 
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -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
> diff --git a/include/linux/notifier.h b/include/linux/notifier.h
> index 540703b..22c2abb 100644
> --- a/include/linux/notifier.h
> +++ b/include/linux/notifier.h
> @@ -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

Are you sure that you can duplicate this value?

curious,

greg k-h