netdev - Re: [RFC PATCH] powerpc/pseries/mobility: notify network peers after migration

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Message-ID: <15e84597-7b5a-1269-f1b8-753268e90741@linux.ibm.com>
Date:   Tue, 5 Nov 2019 22:47:51 -0600
From:   Thomas Falcon <tlfalcon@...ux.ibm.com>
To:     Russell Currey <ruscur@...sell.cc>, linuxppc-dev@...abs.org
Cc:     nathanl@...ux.ibm.com, netdev@...r.kernel.org, msuchanek@...e.com,
        tyreld@...ux.ibm.com
Subject: Re: [RFC PATCH] powerpc/pseries/mobility: notify network peers after
 migration


On 11/5/19 10:13 PM, Russell Currey wrote:
> On Tue, 2019-11-05 at 18:06 -0600, Thomas Falcon wrote:
>> After a migration, it is necessary to send a gratuitous ARP
>> from all running interfaces so that the rest of the network
>> is aware of its new location. However, some supported network
>> devices are unaware that they have been migrated. To avoid network
>> interruptions and other unwanted behavior, force a GARP on all
>> valid, running interfaces as part of the post_mobility_fixup
>> routine.
>>
>> Signed-off-by: Thomas Falcon <tlfalcon@...ux.ibm.com>
> Hi Thomas,
>
>> ---
>>   arch/powerpc/platforms/pseries/mobility.c | 20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/arch/powerpc/platforms/pseries/mobility.c
>> b/arch/powerpc/platforms/pseries/mobility.c
>> index b571285f6c14..c1abc14cf2bb 100644
>> --- a/arch/powerpc/platforms/pseries/mobility.c
>> +++ b/arch/powerpc/platforms/pseries/mobility.c
>> @@ -17,6 +17,9 @@
>>   #include <linux/delay.h>
>>   #include <linux/slab.h>
>>   #include <linux/stringify.h>
>> +#include <linux/netdevice.h>
>> +#include <linux/rtnetlink.h>
>> +#include <net/net_namespace.h>
>>   
>>   #include <asm/machdep.h>
>>   #include <asm/rtas.h>
>> @@ -331,6 +334,8 @@ void post_mobility_fixup(void)
>>   {
>>   	int rc;
>>   	int activate_fw_token;
>> +	struct net_device *netdev;
>> +	struct net *net;
>>   
>>   	activate_fw_token = rtas_token("ibm,activate-firmware");
>>   	if (activate_fw_token == RTAS_UNKNOWN_SERVICE) {
>> @@ -371,6 +376,21 @@ void post_mobility_fixup(void)
>>   	/* Possibly switch to a new RFI flush type */
>>   	pseries_setup_rfi_flush();
>>   
>> +	/* need to force a gratuitous ARP on running interfaces */
>> +	rtnl_lock();
>> +	for_each_net(net) {
>> +		for_each_netdev(net, netdev) {
>> +			if (netif_device_present(netdev) &&
>> +			    netif_running(netdev) &&
>> +			    !(netdev->flags & (IFF_NOARP |
>> IFF_LOOPBACK)))
>> +				call_netdevice_notifiers(NETDEV_NOTIFY_
>> PEERS,
>> +							 netdev);
> Without curly braces following the "if" statment, the second line
> (below) will be executed unconditionally, which I assume with this
> indentation isn't what you want.
>
> (reported by snowpatch)
>
> - Russell

Thanks for catching that! I'll fix that and send a v2 soon.

Tom


>> +				call_netdevice_notifiers(NETDEV_RESEND_
>> IGMP,
>> +							 netdev);
>> +		}
>> +	}
>> +	rtnl_unlock();
>> +
>>   	return;
>>   }
>>