decnet: RCU conversion and get rid of dev_base_lock

While tracking dev_base_lock users, I found decnet used it in
dnet_select_source(), but for a wrong purpose:

Writers only hold RTNL, not dev_base_lock, so readers must use RCU if
they cannot use RTNL.

Adds an rcu_head in struct dn_ifaddr and handle proper RCU management.

Adds __rcu annotation in dn_route as well.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/decnet/dn_fib.c b/net/decnet/dn_fib.c
index 4ab96c15166d..0ef0a81bcd72 100644
--- a/net/decnet/dn_fib.c
+++ b/net/decnet/dn_fib.c
@@ -610,10 +610,12 @@ static void dn_fib_del_ifaddr(struct dn_ifaddr *ifa)
         /* Scan device list */
         rcu_read_lock();
         for_each_netdev_rcu(&init_net, dev) {
-                dn_db = dev->dn_ptr;
+                dn_db = rcu_dereference(dev->dn_ptr);
                 if (dn_db == NULL)
                         continue;
-                for(ifa2 = dn_db->ifa_list; ifa2; ifa2 = ifa2->ifa_next) {
+                for (ifa2 = rcu_dereference(dn_db->ifa_list);
+                     ifa2 != NULL;
+                     ifa2 = rcu_dereference(ifa2->ifa_next)) {
                         if (ifa2->ifa_local == ifa->ifa_local) {
                                 found_it = 1;
                                 break;