[PATCH 4.4 03/66] ipv6: fix sparse warning on rt6i_node

Greg Kroah-Hartman
2017-09-24T20:34:57Z

From: Wei Wang <weiwan@google.com>

[ 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 <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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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(-)

--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -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;

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -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);
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -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;
}
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -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,