ipv6: fix sparse warning on rt6i_node

Commit c5cff8561d2d adds rcu grace period before freeing fib6_node. This
generates a new sparse warning on rt->rt6i_node related code:
  net/ipv6/route.c:1394:30: error: incompatible types in comparison
  expression (different address spaces)
  ./include/net/ip6_fib.h:187:14: error: incompatible types in comparison
  expression (different address spaces)

This commit adds "__rcu" tag for rt6i_node and makes sure corresponding
rcu API is used for it.
After this fix, sparse no longer generates the above warning.

Fixes: c5cff8561d2d ("ipv6: add rcu grace period before freeing fib6_node")
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index e9c59db92942f02a5def4bd45576283c6995f6ad..af509f801084dcf19a27f9d4c82344c5e54fe792 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -105,7 +105,7 @@ struct rt6_info {
         * the same cache line.
         */
        struct fib6_table               *rt6i_table;
-       struct fib6_node                *rt6i_node;
+       struct fib6_node __rcu          *rt6i_node;
 
        struct in6_addr                 rt6i_gateway;
 

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 3c46e9513a31d04eeb1e76384f146b759ae38eed..936e9ab4dda5453ce30b8640b85693b9728502fd 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5556,7 +5556,7 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
                 * our DAD process, so we don't need
                 * to do it again
                 */
-               if (!(ifp->rt->rt6i_node))
+               if (!rcu_access_pointer(ifp->rt->rt6i_node))
                        ip6_ins_rt(ifp->rt);
                if (ifp->idev->cnf.forwarding)
                        addrconf_join_anycast(ifp);

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index a5ebf86f6be810f23343b7bc824b8587e0c4425a..10b4b1f8b838854fc2f2d3b9ac0b04c06a700b2f 100644 (file)
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -889,7 +889,7 @@ add:
 
                rt->dst.rt6_next = iter;
                *ins = rt;
-               rt->rt6i_node = fn;
+               rcu_assign_pointer(rt->rt6i_node, fn);
                atomic_inc(&rt->rt6i_ref);
                if (!info->skip_notify)
                        inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
@@ -915,7 +915,7 @@ add:
                        return err;
 
                *ins = rt;
-               rt->rt6i_node = fn;
+               rcu_assign_pointer(rt->rt6i_node, fn);
                rt->dst.rt6_next = iter->dst.rt6_next;
                atomic_inc(&rt->rt6i_ref);
                if (!info->skip_notify)
@@ -1480,8 +1480,9 @@ static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
 
 int fib6_del(struct rt6_info *rt, struct nl_info *info)
 {
+       struct fib6_node *fn = rcu_dereference_protected(rt->rt6i_node,
+                                   lockdep_is_held(&rt->rt6i_table->tb6_lock));
        struct net *net = info->nl_net;
-       struct fib6_node *fn = rt->rt6i_node;
        struct rt6_info **rtp;
 
 #if RT6_DEBUG >= 2
@@ -1670,7 +1671,9 @@ static int fib6_clean_node(struct fib6_walker *w)
                        if (res) {
 #if RT6_DEBUG >= 2
                                pr_debug("%s: del failed: rt=%p@%p err=%d\n",
-                                        __func__, rt, rt->rt6i_node, res);
+                                        __func__, rt,
+                                        rcu_access_pointer(rt->rt6i_node),
+                                        res);
 #endif
                                continue;
                        }

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 48c8c92dcbd39263b97672f123dfa63a8c6860da..86fb2411e2bda7d148a6467411b4d025bd4c397c 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1383,7 +1383,8 @@ static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu)
 static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
 {
        return !(rt->rt6i_flags & RTF_CACHE) &&
-               (rt->rt6i_flags & RTF_PCPU || rt->rt6i_node);
+               (rt->rt6i_flags & RTF_PCPU ||
+                rcu_access_pointer(rt->rt6i_node));
 }
 
 static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,