[PATCH] UBUNTU: SAUCE: net/ipv4: Always flush route cache on unregister batch call

[Chris J Arges]

From: Stefan Bader <stefan.bader at canonical.com>

When doing (for example) a connect to an unused port on localhost
in a new net namespace, it was observed that lo could not be
removed immediately because there were still references on it.
To release those references could take a very long time (up to
five minutes).

This was tracked down to an element in the route cache which was
supposed to be dropped by a notify call with sending a
NETDEVICE_UNREGISTER_BATCH message, but as in_dev is already unset
then, the case statement never was executed.

Move the handling of that notification up to be done regardless of
the state of in_dev.

BugLink: http://bugs.launchpad.net/bugs/1021471

Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
Signed-off-by: Chris J Arges <chris.j.arges at canonical.com>
---
 net/ipv4/fib_frontend.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 92fc5f6..5085d48 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -999,6 +999,14 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
 		fib_disable_ip(dev, 2, -1);
 		return NOTIFY_DONE;
 	}
+	if (event == NETDEV_UNREGISTER_BATCH) {
+		/* The batch unregister is only called on the first
+		 * device in the list of devices being unregistered.
+		 * Therefore we should not pass dev_net(dev) in here.
+		 */
+		rt_cache_flush_batch(NULL);
+		return NOTIFY_DONE;
+	}
 
 	if (!in_dev)
 		return NOTIFY_DONE;
@@ -1021,13 +1029,6 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
 	case NETDEV_CHANGE:
 		rt_cache_flush(dev_net(dev), 0);
 		break;
-	case NETDEV_UNREGISTER_BATCH:
-		/* The batch unregister is only called on the first
-		 * device in the list of devices being unregistered.
-		 * Therefore we should not pass dev_net(dev) in here.
-		 */
-		rt_cache_flush_batch(NULL);
-		break;
 	}
 	return NOTIFY_DONE;
 }
-- 
1.9.1