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>

1 files changed, 5 insertions, 3 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index fc1fac2a0528..3342ee64f2e3 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;