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Patch "ipv6: fix sparse warning on rt6i_node" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Sep 15, 2017

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This is a note to let you know that I've just added the patch titled

ipv6: fix sparse warning on rt6i_node

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ipv6-fix-sparse-warning-on-rt6i_node.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Fri Sep 15 10:03:45 PDT 2017

From: Wei Wang <[email protected]>
Date: Fri, 25 Aug 2017 15:03:10 -0700
Subject: ipv6: fix sparse warning on rt6i_node

From: Wei Wang <[email protected]>

[ Upstream commit 4e587ea71bf924f7dac621f1351653bd41e446cb ]

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 <[email protected]>
Acked-by Eric Dumazet <[email protected]>
Acked-by Martin KaFai Lau <[email protected]>
Signed-off-by David S. Miller <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 include/net/ip6_fib.h |    2 +-
 net/ipv6/addrconf.c   |    2 +-
 net/ipv6/ip6_fib.c    |   11 +++++++----
 net/ipv6/route.c      |    3 ++-
 4 files changed, 11 insertions(+), 7 deletions(-)
include/net/ip6_fib.h +1 -1
@@ -103,7 +103,7 @@ 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;
net/ipv6/addrconf.c +1 -1
@@ -5152,7 +5152,7 @@ static void __ipv6_ifa_notify(int event,
 		 * 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);
net/ipv6/ip6_fib.c +7 -4
@@ -869,7 +869,7 @@ add:
 
 		rt->dst.rt6_next = iter;
 		*ins = rt;
-		rt->rt6i_node = fn;
+		rcu_assign_pointer(rt->rt6i_node, fn);
 		atomic_inc(&rt->rt6i_ref);
 		inet6_rt_notify(RTM_NEWROUTE, rt, info, 0);
 		info->nl_net->ipv6.rt6_stats->fib_rt_entries++;

@@ -894,7 +894,7 @@ 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);
 		inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);

@@ -1454,8 +1454,9 @@ static void fib6_del_route(struct fib6_n
 
 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

@@ -1644,7 +1645,9 @@ static int fib6_clean_node(struct fib6_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;
 			}
net/ipv6/route.c +2 -1
@@ -1342,7 +1342,8 @@ static void rt6_do_update_pmtu(struct rt
 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,

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/ipv6-fix-sparse-warning-on-rt6i_node.patch queue-4.4/tcp-initialize-rcv_mss-to-tcp_min_mss-instead-of-0.patch queue-4.4/ipv6-add-rcu-grace-period-before-freeing-fib6_node.patch