Subject: Re: [PATCH] bonding: If IP route look-up to send an ARP fails, mark in bonding structure as no ARP sent.

From: Veaceslav Falico <[email-masked]>
Date: Thu, 21 Nov 2013 12:10:22 +0100

On Wed, Nov 20, 2013 at 04:53:20PM -0800, rama nichanamatlu wrote:
>During the creation of VLAN's atop bonding the underlying interfaces 
>are made part of VLAN's, and at the same bonding driver gets aware 
>that VLAN's exists above it and hence would consult IP routing for 
>every ARP to  be sent to determine the route which tells bonding 
>driver the correct VLAN tag to attach to the outgoing ARP packet. 
>But, during the VLAN creation when vlan driver puts the underlying 
>interface into default vlan and then actual vlan, in-between this if 
>bonding driver consults the IP for a route, IP fails to provide a 
>correct route and upon which bonding driver drops the ARP packet. ARP 
>monitor when it
>comes around next time, sees no ARP response and fails-over to the 
>next available slave. Consulting for a IP route, 
>ip_route_output(),happens in bond_arp_send_all().

bonding works as expected - nothing to fix here. And even as a
workaround/hack - I'm not sure we need that to suppress one failover *only*
when vlan is added on top.

>
>To prevent this false fail-over, when bonding driver fails to send an 
>ARP out it marks in its private structure, bonding{},  not to expect 
>an ARP response, when ARP monitor comes around next time ARP sending 
>will be tried again.
>
>Extensively tested in a VM environment; sr-iov intf->bonding 
>intf->vlan intf. All virtual interfaces created at boot time.
>
>Orabug: 17172660
>Signed-off-by: Venkat Venkatsubra <[email-masked]>
>Signed-off-by: Rama Nichanamatlu <[email-masked]>
>---
> drivers/net/bonding/bond_main.c | 13 ++++++++-----
> drivers/net/bonding/bonding.h   |  1 +
> 2 files changed, 9 insertions(+), 5 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c 
>b/drivers/net/bonding/bond_main.c
>index dde6b4a..d475161 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -2661,7 +2661,7 @@ static int bond_has_this_ip(struct bonding 
>*bond, __be32 ip)
>  * switches in VLAN mode (especially if ports are configured as
>  * "native" to a VLAN) might not pass non-tagged frames.
>  */
>-static void bond_arp_send(struct net_device *slave_dev, int arp_op, 
>__be32 dest_ip, __be32 src_ip, unsigned short vlan_id)
>+static void bond_arp_send(struct bonding *bond, struct net_device 
>*slave_dev, int arp_op, __be32 dest_ip, __be32 src_ip, unsigned short 
>vlan_id)
> {
> 	struct sk_buff *skb;
> @@ -2683,6 +2683,7 @@ static void bond_arp_send(struct net_device 
>*slave_dev, int arp_op, __be32 dest_
> 		}
> 	}
> 	arp_xmit(skb);
>+	bond->arp_sent=true;
> }
>  @@ -2700,7 +2701,7 @@ static void bond_arp_send_all(struct bonding 
>*bond, struct slave *slave)
> 		pr_debug("basa: target %x\n", targets[i]);
> 		if (!bond->vlgrp) {
> 			pr_debug("basa: empty vlan: arp_send\n");
>-			bond_arp_send(slave->dev, ARPOP_REQUEST, targets[i],
>+			bond_arp_send(bond, slave->dev, ARPOP_REQUEST, targets[i],
> 				      bond->master_ip, 0);
> 			continue;
> 		}
>@@ -2726,7 +2727,7 @@ static void bond_arp_send_all(struct bonding 
>*bond, struct slave *slave)
> 		if (rt->dst.dev == bond->dev) {
> 			ip_rt_put(rt);
> 			pr_debug("basa: rtdev == bond->dev: arp_send\n");
>-			bond_arp_send(slave->dev, ARPOP_REQUEST, targets[i],
>+			bond_arp_send(bond, slave->dev, ARPOP_REQUEST, targets[i],
> 				      bond->master_ip, 0);
> 			continue;
> 		}
>@@ -2744,7 +2745,7 @@ static void bond_arp_send_all(struct bonding 
>*bond, struct slave *slave)
>  		if (vlan_id) {
> 			ip_rt_put(rt);
>-			bond_arp_send(slave->dev, ARPOP_REQUEST, targets[i],
>+			bond_arp_send(bond, slave->dev, ARPOP_REQUEST, targets[i],
> 				      vlan->vlan_ip, vlan_id);
> 			continue;
> 		}
>@@ -3206,7 +3207,7 @@ void bond_activebackup_arp_mon(struct 
>work_struct *work)
>  	should_notify_peers = bond_should_notify_peers(bond);
> -	if (bond_ab_arp_inspect(bond, delta_in_ticks)) {
>+	if (bond->arp_sent && bond_ab_arp_inspect(bond, delta_in_ticks)) {
> 		read_unlock(&bond->lock);
> 		rtnl_lock();
> 		read_lock(&bond->lock);
>@@ -3218,6 +3219,7 @@ void bond_activebackup_arp_mon(struct 
>work_struct *work)
> 		read_lock(&bond->lock);
> 	}
> +	bond->arp_sent=false;
> 	bond_ab_arp_probe(bond);
>  re_arm:
>@@ -4425,6 +4427,7 @@ static void bond_setup(struct net_device *bond_dev)
>  	bond_dev->hw_features &= ~(NETIF_F_ALL_CSUM & ~NETIF_F_NO_CSUM);
> 	bond_dev->features |= bond_dev->hw_features;
>+	bond->arp_sent=false;
> }
>  static void bond_work_cancel_all(struct bonding *bond)
>diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
>index e9a3c56..3878bbd 100644
>--- a/drivers/net/bonding/bonding.h
>+++ b/drivers/net/bonding/bonding.h
>@@ -253,6 +253,7 @@ struct bonding {
> 	/* debugging suport via debugfs */
> 	struct	 dentry *debug_dir;
> #endif /* CONFIG_DEBUG_FS */
>+        bool arp_sent;
> };
>  #define bond_slave_get_rcu(dev) \
>-- 
>1.8.2.1
>