netdev - [86/90] net: Fix userspace RTM

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Message-Id: <20091217011609.228623383@mini.kroah.org>
Date:	Wed, 16 Dec 2009 17:15:37 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org,
	David Miller <davem@...emloft.net>
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	netdev@...r.kernel.org, marcel@...tmann.org,
	"Eric W. Biederman" <ebiederm@...stanetworks.com>
Subject: [86/90] net: Fix userspace RTM_NEWLINK notifications.

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------

commit d90a909e1f3e006a1d57fe11fd417173b6494701 upstream.

I received some bug reports about userspace programs having problems
because after RTM_NEWLINK was received they could not immeidate
access files under /proc/sys/net/ because they had not been
registered yet.

The problem was trivailly fixed by moving the userspace
notification from rtnetlink_event to the end of register_netdevice.

Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
Cc: David Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 net/core/dev.c       |   11 +++++++++++
 net/core/rtnetlink.c |    4 +---
 2 files changed, 12 insertions(+), 3 deletions(-)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4808,6 +4808,11 @@ int register_netdevice(struct net_device
 		rollback_registered(dev);
 		dev->reg_state = NETREG_UNREGISTERED;
 	}
+	/*
+	 *	Prevent userspace races by waiting until the network
+	 *	device is fully setup before sending notifications.
+	 */
+	rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
 
 out:
 	return ret;
@@ -5343,6 +5348,12 @@ int dev_change_net_namespace(struct net_
 	/* Notify protocols, that a new device appeared. */
 	call_netdevice_notifiers(NETDEV_REGISTER, dev);
 
+	/*
+	 *	Prevent userspace races by waiting until the network
+	 *	device is fully setup before sending notifications.
+	 */
+	rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
+
 	synchronize_net();
 	err = 0;
 out:
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1347,13 +1347,11 @@ static int rtnetlink_event(struct notifi
 	case NETDEV_UNREGISTER:
 		rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);
 		break;
-	case NETDEV_REGISTER:
-		rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
-		break;
 	case NETDEV_UP:
 	case NETDEV_DOWN:
 		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
 		break;
+	case NETDEV_REGISTER:
 	case NETDEV_CHANGE:
 	case NETDEV_GOING_DOWN:
 		break;


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