netdev - Re: [PATCH net-next 1/6] bonding: verify if bond has ip only once on arp validate

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Message-ID: <20130619184838.GA22345@redhat.com>
Date:	Wed, 19 Jun 2013 20:48:38 +0200
From:	Veaceslav Falico <vfalico@...hat.com>
To:	Jay Vosburgh <fubar@...ibm.com>
Cc:	netdev@...r.kernel.org, andy@...yhouse.net, davem@...emloft.net,
	linux@...2.net, nicolas.2p.debian@...e.fr, rick.jones2@...com
Subject: Re: [PATCH net-next 1/6] bonding: verify if bond has ip only once on
 arp validate

On Wed, Jun 19, 2013 at 10:50:24AM -0700, Jay Vosburgh wrote:
>Veaceslav Falico <vfalico@...hat.com> wrote:
>
>>It's extra work to verify bond's ip presence for every slave, so take it
>>out of the loop.
>
>	The current code doesn't verify for every slave (target address,
>actually).  The call to bond_has_this_ip() happens at most once, if the
>sip (source IP) matches the arp_ip_target being inspected, after which
>the function returns.
>
>	I can see that the patch will bypass the loop entirely if the
>bond lacks the IP, but I'm not sure that's a meaningful improvement,
>since it changes from calling bond_has_this_ip 0 or 1 times to always 1
>time.

Yep, you're right, I've misread the code.

It's just not worth it, will drop this patch in v2.

>
>	-J
>
>
>>Signed-off-by: Veaceslav Falico <vfalico@...hat.com>
>>---
>> drivers/net/bonding/bond_main.c |   13 ++++++++-----
>> 1 files changed, 8 insertions(+), 5 deletions(-)
>>
>>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>>index bc1246f..3d8b5ba 100644
>>--- a/drivers/net/bonding/bond_main.c
>>+++ b/drivers/net/bonding/bond_main.c
>>@@ -2602,13 +2602,16 @@ static void bond_validate_arp(struct bonding *bond, struct slave *slave, __be32
>> 	int i;
>> 	__be32 *targets = bond->params.arp_targets;
>>
>>+	if (!bond_has_this_ip(bond, tip)) {
>>+		pr_debug("bva: tip %pI4 not found\n", &tip);
>>+		return;
>>+	}
>>+
>> 	for (i = 0; (i < BOND_MAX_ARP_TARGETS) && targets[i]; i++) {
>>-		pr_debug("bva: sip %pI4 tip %pI4 t[%d] %pI4 bhti(tip) %d\n",
>>-			 &sip, &tip, i, &targets[i],
>>-			 bond_has_this_ip(bond, tip));
>>+		pr_debug("bva: sip %pI4 tip %pI4 t[%d] %pI4 bhti(tip)\n",
>>+			 &sip, &tip, i, &targets[i]);
>> 		if (sip == targets[i]) {
>>-			if (bond_has_this_ip(bond, tip))
>>-				slave->last_arp_rx = jiffies;
>>+			slave->last_arp_rx = jiffies;
>> 			return;
>> 		}
>> 	}
>>--
>>1.7.1
>>
>
>---
>	-Jay Vosburgh, IBM Linux Technology Center, fubar@...ibm.com
>
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