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From patchwork Tue May 21 10:23:44 2013
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Subject: [v2,net-next] arp: flush arp cache on IFF_NOARP change
Date: Tue, 21 May 2013 00:23:44 -0000
From: =?utf-8?q?Timo_Ter=C3=A4s?= <timo.teras@iki.fi>
X-Patchwork-Id: 245256
Message-Id: <1369131824-6318-1-git-send-email-timo.teras@iki.fi>
To: David Miller <davem@davemloft.net>, netdev@vger.kernel.org, kaber@trash.net
Cc: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>
IFF_NOARP affects what kind of neighbor entries are created
(nud NOARP or nud INCOMPLETE). If the flag changes, flush the arp
cache to refresh all entries.
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
---
> This patch makes no sense at all.
>
> The state bit in ->priv_flags is a boolean stating whether the
> notified should do something or not.
>
> But you're setting it to match what IFF_NOARP is.
>
> You should set it any time IFF_NOARP _changes_, and then clear
> the bit when the notifier clears the neighbour entries.
IFF_NOARP_CHANGED is set according to "changes = dev->flags ^ old_flags;"
which reflect the change. But I agree that the clearing out bit was
misplaced. This is especially true as it seems NETDEV_CHANGE can be
notified from another place too.
I've updated the if.h comment to state that the bit is valid only during
NETDEV_CHANGE notifier. And __dev_notify_flags is updated to always clear
the bit after notifiers are done.
include/uapi/linux/if.h | 2 ++
net/core/dev.c | 6 +++++-
net/ipv4/arp.c | 4 ++++
3 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/if.h b/include/uapi/linux/if.h
index 1ec407b..1be8b35 100644
--- a/include/uapi/linux/if.h
+++ b/include/uapi/linux/if.h
@@ -83,6 +83,8 @@
#define IFF_SUPP_NOFCS 0x80000 /* device supports sending custom FCS */
#define IFF_LIVE_ADDR_CHANGE 0x100000 /* device supports hardware address
* change when it's running */
+#define IFF_NOARP_CHANGED 0x200000 /* Set during NETDEV_CHANGE notifier
+ * if IFF_NOARP has changed */
#define IF_GET_IFACE 0x0001 /* for querying only */
diff --git a/net/core/dev.c b/net/core/dev.c
index 18e9730..ce30761 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4699,8 +4699,12 @@ void __dev_notify_flags(struct net_device *dev, unsigned int old_flags)
}
if (dev->flags & IFF_UP &&
- (changes & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI | IFF_VOLATILE)))
+ (changes & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI | IFF_VOLATILE))) {
+ if (changes & IFF_NOARP)
+ dev->priv_flags |= IFF_NOARP_CHANGED;
call_netdevice_notifiers(NETDEV_CHANGE, dev);
+ dev->priv_flags &= ~IFF_NOARP_CHANGED;
+ }
}
/**
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 247ec19..375b2f2 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1241,6 +1241,10 @@ static int arp_netdev_event(struct notifier_block *this, unsigned long event,
neigh_changeaddr(&arp_tbl, dev);
rt_cache_flush(dev_net(dev));
break;
+ case NETDEV_CHANGE:
+ if (dev->priv_flags & IFF_NOARP_CHANGED)
+ neigh_changeaddr(&arp_tbl, dev);
+ break;
default:
break;
}
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