netdev - [PATCH] net: allow interface to be set into vrf if a vif in same vrf

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Date:   Mon, 26 Feb 2018 16:48:56 +0000
From:   Mike Manning <mmanning@...tta.mail-att.com>
To:     netdev@...r.kernel.org, dsahern@...il.com
Subject: [PATCH] net: allow interface to be set into vrf if a vif in same vrf

Setting an interface into a vrf fails with 'RTNETLINK answers: File
exists' if one of its vifs is already in the same vrf. As the vrf is an
upper device of the vif, it is also showing up as an upper device of
the interface itself. The solution is to restrict this check to devices
other than master. As only one master device can be linked to a device,
in this case the check is for the upper device (vrf) to be linked to as
being the master device rather than any other upper device.

Signed-off-by: Mike Manning <mmanning@....com>
---
 net/core/dev.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index d4362be..2cedf52 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6396,6 +6396,7 @@ static int __netdev_upper_dev_link(struct net_device *dev,
 		.linking = true,
 		.upper_info = upper_info,
 	};
+	struct net_device *master_dev;
 	int ret = 0;
 
 	ASSERT_RTNL();
@@ -6407,11 +6408,14 @@ static int __netdev_upper_dev_link(struct net_device *dev,
 	if (netdev_has_upper_dev(upper_dev, dev))
 		return -EBUSY;
 
-	if (netdev_has_upper_dev(dev, upper_dev))
-		return -EEXIST;
-
-	if (master && netdev_master_upper_dev_get(dev))
-		return -EBUSY;
+	if (!master) {
+		if (netdev_has_upper_dev(dev, upper_dev))
+			return -EEXIST;
+	} else {
+		master_dev = netdev_master_upper_dev_get(dev);
+		if (master_dev)
+			return master_dev == upper_dev ? -EEXIST : -EBUSY;
+	}
 
 	ret = call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
 					    &changeupper_info.info);
-- 
2.1.4