ipv6: Use state_lock to protect ifa state

This patch makes use of the new state_lock to synchronise between
updates to the ifa state.  This fixes the issue where a remotely
triggered address deletion (through DAD failure) coincides with a
local administrative address deletion, causing certain actions to
be performed twice incorrectly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 4 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 4e5ad9de1679..2e42162c9042 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -715,13 +715,20 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
 {
         struct inet6_ifaddr *ifa, *ifn;
         struct inet6_dev *idev = ifp->idev;
+        int state;
         int hash;
         int deleted = 0, onlink = 0;
         unsigned long expires = jiffies;
 
         hash = ipv6_addr_hash(&ifp->addr);
 
+        spin_lock_bh(&ifp->state_lock);
+        state = ifp->state;
         ifp->state = INET6_IFADDR_STATE_DEAD;
+        spin_unlock_bh(&ifp->state_lock);
+
+        if (state == INET6_IFADDR_STATE_DEAD)
+                goto out;
 
         spin_lock_bh(&addrconf_hash_lock);
         hlist_del_init_rcu(&ifp->addr_lst);
@@ -819,6 +826,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
                 dst_release(&rt->u.dst);
         }
 
+out:
         in6_ifa_put(ifp);
 }
 
@@ -2626,6 +2634,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
         struct inet6_dev *idev;
         struct inet6_ifaddr *ifa;
         LIST_HEAD(keep_list);
+        int state;
 
         ASSERT_RTNL();
 
@@ -2666,7 +2675,6 @@ static int addrconf_ifdown(struct net_device *dev, int how)
                 ifa = list_first_entry(&idev->tempaddr_list,
                                        struct inet6_ifaddr, tmp_list);
                 list_del(&ifa->tmp_list);
-                ifa->state = INET6_IFADDR_STATE_DEAD;
                 write_unlock_bh(&idev->lock);
                 spin_lock_bh(&ifa->lock);
 
@@ -2704,23 +2712,34 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
                         /* Flag it for later restoration when link comes up */
                         ifa->flags |= IFA_F_TENTATIVE;
-                        in6_ifa_hold(ifa);
+
                         write_unlock_bh(&idev->lock);
+
+                        in6_ifa_hold(ifa);
                 } else {
                         list_del(&ifa->if_list);
-                        ifa->state = INET6_IFADDR_STATE_DEAD;
-                        write_unlock_bh(&idev->lock);
 
                         /* clear hash table */
                         spin_lock_bh(&addrconf_hash_lock);
                         hlist_del_init_rcu(&ifa->addr_lst);
                         spin_unlock_bh(&addrconf_hash_lock);
+
+                        write_unlock_bh(&idev->lock);
+                        spin_lock_bh(&ifa->state_lock);
+                        state = ifa->state;
+                        ifa->state = INET6_IFADDR_STATE_DEAD;
+                        spin_unlock_bh(&ifa->state_lock);
+
+                        if (state == INET6_IFADDR_STATE_DEAD)
+                                goto put_ifa;
                 }
 
                 __ipv6_ifa_notify(RTM_DELADDR, ifa);
                 if (ifa->state == INET6_IFADDR_STATE_DEAD)
                         atomic_notifier_call_chain(&inet6addr_chain,
                                                    NETDEV_DOWN, ifa);
+
+put_ifa:
                 in6_ifa_put(ifa);
 
                 write_lock_bh(&idev->lock);