[PATCH net-next 1/6] ipv6: prepare RCU lookups for idev->addr_list

[Eric Dumazet]

inet6_ifa_finish_destroy() already uses kfree_rcu() to free
inet6_ifaddr structs.

We need to use proper list additions/deletions in order
to allow readers to use RCU instead of idev->lock rwlock.

Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 net/ipv6/addrconf.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 
9854d93e45bb5ca919d55e6b875f7dc392a5dae5..d1ff0955b709eaa6b5d94bd8d740334eb1eed6d7
 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -945,7 +945,7 @@ ipv6_link_dev_addr(struct inet6_dev *idev, struct 
inet6_ifaddr *ifp)
                        break;
        }
 
-       list_add_tail(&ifp->if_list, p);
+       list_add_tail_rcu(&ifp->if_list, p);
 }
 
 static u32 inet6_addr_hash(const struct in6_addr *addr)
@@ -1204,7 +1204,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
        if (ifp->flags & IFA_F_PERMANENT && !(ifp->flags & IFA_F_NOPREFIXROUTE))
                action = check_cleanup_prefix_route(ifp, &expires);
 
-       list_del_init(&ifp->if_list);
+       list_del_rcu(&ifp->if_list);
        __in6_ifa_put(ifp);
 
        write_unlock_bh(&ifp->idev->lock);
@@ -3562,7 +3562,6 @@ static int addrconf_ifdown(struct net_device *dev, int 
how)
        struct net *net = dev_net(dev);
        struct inet6_dev *idev;
        struct inet6_ifaddr *ifa, *tmp;
-       struct list_head del_list;
        int _keep_addr;
        bool keep_addr;
        int state, i;
@@ -3654,7 +3653,6 @@ static int addrconf_ifdown(struct net_device *dev, int 
how)
         */
        keep_addr = (!how && _keep_addr > 0 && !idev->cnf.disable_ipv6);
 
-       INIT_LIST_HEAD(&del_list);
        list_for_each_entry_safe(ifa, tmp, &idev->addr_list, if_list) {
                struct rt6_info *rt = NULL;
                bool keep;
@@ -3663,8 +3661,6 @@ static int addrconf_ifdown(struct net_device *dev, int 
how)
 
                keep = keep_addr && (ifa->flags & IFA_F_PERMANENT) &&
                        !addr_is_local(&ifa->addr);
-               if (!keep)
-                       list_move(&ifa->if_list, &del_list);
 
                write_unlock_bh(&idev->lock);
                spin_lock_bh(&ifa->lock);
@@ -3698,19 +3694,14 @@ static int addrconf_ifdown(struct net_device *dev, int 
how)
                }
 
                write_lock_bh(&idev->lock);
+               if (!keep) {
+                       list_del_rcu(&ifa->if_list);
+                       in6_ifa_put(ifa);
+               }
        }
 
        write_unlock_bh(&idev->lock);
 
-       /* now clean up addresses to be removed */
-       while (!list_empty(&del_list)) {
-               ifa = list_first_entry(&del_list,
-                                      struct inet6_ifaddr, if_list);
-               list_del(&ifa->if_list);
-
-               in6_ifa_put(ifa);
-       }
-
        /* Step 5: Discard anycast and multicast list */
        if (how) {
                ipv6_ac_destroy_dev(idev);
-- 
2.14.2.920.gcf0c67979c-goog