ipv6: clean up anycast when an interface is destroyed

If we try to rmmod the driver for an interface while sockets with
setsockopt(JOIN_ANYCAST) are alive, some refcounts aren't cleaned up
and we get stuck on:

  unregister_netdevice: waiting for ens3 to become free. Usage count = 1

If we LEAVE_ANYCAST/close everything before rmmod'ing, there is no
problem.

We need to perform a cleanup similar to the one for multicast in
addrconf_ifdown(how == 1).

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 26 insertions, 3 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index fc1fac2..3342ee6 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3094,11 +3094,13 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
 	write_unlock_bh(&idev->lock);
 
-	/* Step 5: Discard multicast list */
-	if (how)
+	/* Step 5: Discard anycast and multicast list */
+	if (how) {
+		ipv6_ac_destroy_dev(idev);
 		ipv6_mc_destroy_dev(idev);
-	else
+	} else {
 		ipv6_mc_down(idev);
+	}
 
 	idev->tstamp = jiffies;
 
diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index ff2de7d..9a38684 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -351,6 +351,27 @@ static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 	return __ipv6_dev_ac_dec(idev, addr);
 }
 
+void ipv6_ac_destroy_dev(struct inet6_dev *idev)
+{
+	struct ifacaddr6 *aca;
+
+	write_lock_bh(&idev->lock);
+	while ((aca = idev->ac_list) != NULL) {
+		idev->ac_list = aca->aca_next;
+		write_unlock_bh(&idev->lock);
+
+		addrconf_leave_solict(idev, &aca->aca_addr);
+
+		dst_hold(&aca->aca_rt->dst);
+		ip6_del_rt(aca->aca_rt);
+
+		aca_put(aca);
+
+		write_lock_bh(&idev->lock);
+	}
+	write_unlock_bh(&idev->lock);
+}
+
 /*
  *	check if the interface has this anycast address
  *	called with rcu_read_lock()