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Commit 810e530b authored by David Ahern's avatar David Ahern Committed by David S. Miller
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net: vrf: Switch dst dev to loopback on device delete 



Attempting to delete a VRF device with a socket bound to it can stall:

  unregister_netdevice: waiting for red to become free. Usage count = 1

The unregister is waiting for the dst to be released and with it
references to the vrf device. Similar to dst_ifdown switch the dst
dev to loopback on delete for all of the dst's for the vrf device
and release the references to the vrf device.

Fixes: 193125db ("net: Introduce VRF device driver")
Fixes: 35402e31 ("net: Add IPv6 support to VRF device")
Signed-off-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 042ce722

drivers/net/vrf.c

+42 −13
Original line number Diff line number Diff line
@@ -378,23 +378,37 @@ static int vrf_output6(struct net *net, struct sock *sk, struct sk_buff *skb) 
}



/* holding rtnl */

static void vrf_rt6_release(struct net_vrf *vrf)

static void vrf_rt6_release(struct net_device *dev, struct net_vrf *vrf)

{

	struct rt6_info *rt6 = rtnl_dereference(vrf->rt6);

	struct rt6_info *rt6_local = rtnl_dereference(vrf->rt6_local);

	struct net *net = dev_net(dev);

	struct dst_entry *dst;



	RCU_INIT_POINTER(vrf->rt6, NULL);

	RCU_INIT_POINTER(vrf->rt6_local, NULL);

	synchronize_rcu();



	if (rt6)

		dst_release(&rt6->dst);

	/* move dev in dst's to loopback so this VRF device can be deleted

	 * - based on dst_ifdown

	 */

	if (rt6) {

		dst = &rt6->dst;

		dev_put(dst->dev);

		dst->dev = net->loopback_dev;

		dev_hold(dst->dev);

		dst_release(dst);

	}



	if (rt6_local) {

		if (rt6_local->rt6i_idev)

			in6_dev_put(rt6_local->rt6i_idev);



		dst_release(&rt6_local->dst);

		dst = &rt6_local->dst;

		dev_put(dst->dev);

		dst->dev = net->loopback_dev;

		dev_hold(dst->dev);

		dst_release(dst);

	}

}
@@ -449,7 +463,7 @@ static int vrf_rt6_create(struct net_device *dev) 
	return rc;

}

#else

static void vrf_rt6_release(struct net_vrf *vrf)

static void vrf_rt6_release(struct net_device *dev, struct net_vrf *vrf)

{

}
@@ -518,20 +532,35 @@ static int vrf_output(struct net *net, struct sock *sk, struct sk_buff *skb) 
}



/* holding rtnl */

static void vrf_rtable_release(struct net_vrf *vrf)

static void vrf_rtable_release(struct net_device *dev, struct net_vrf *vrf)

{

	struct rtable *rth = rtnl_dereference(vrf->rth);

	struct rtable *rth_local = rtnl_dereference(vrf->rth_local);

	struct net *net = dev_net(dev);

	struct dst_entry *dst;



	RCU_INIT_POINTER(vrf->rth, NULL);

	RCU_INIT_POINTER(vrf->rth_local, NULL);

	synchronize_rcu();



	if (rth)

		dst_release(&rth->dst);

	/* move dev in dst's to loopback so this VRF device can be deleted

	 * - based on dst_ifdown

	 */

	if (rth) {

		dst = &rth->dst;

		dev_put(dst->dev);

		dst->dev = net->loopback_dev;

		dev_hold(dst->dev);

		dst_release(dst);

	}



	if (rth_local)

		dst_release(&rth_local->dst);

	if (rth_local) {

		dst = &rth_local->dst;

		dev_put(dst->dev);

		dst->dev = net->loopback_dev;

		dev_hold(dst->dev);

		dst_release(dst);

	}

}



static int vrf_rtable_create(struct net_device *dev)
@@ -633,8 +662,8 @@ static void vrf_dev_uninit(struct net_device *dev) 
	struct net_device *port_dev;

	struct list_head *iter;



	vrf_rtable_release(vrf);

	vrf_rt6_release(vrf);

	vrf_rtable_release(dev, vrf);

	vrf_rt6_release(dev, vrf);



	netdev_for_each_lower_dev(dev, port_dev, iter)

		vrf_del_slave(dev, port_dev);
@@ -669,7 +698,7 @@ static int vrf_dev_init(struct net_device *dev) 
	return 0;



out_rth:

	vrf_rtable_release(vrf);

	vrf_rtable_release(dev, vrf);

out_stats:

	free_percpu(dev->dstats);

	dev->dstats = NULL;