On Fri, Aug 25, 2017 at 03:03:10PM -0700, Wei Wang wrote:
> From: Wei Wang <wei...@google.com>
>
> 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 <wei...@google.com>
> Acked-by: Eric Dumazet <eduma...@google.com>
Acked-by: Martin KaFai Lau <ka...@fb.com>
> ---
> 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(-)
>
> diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
> index e9c59db92942..af509f801084 100644
> --- 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 3c46e9513a31..936e9ab4dda5 100644
> --- 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 a5ebf86f6be8..10b4b1f8b838 100644
> --- a/net/ipv6/ip6_fib.c
> +++ b/net/ipv6/ip6_fib.c
> @@ -889,7 +889,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct
> rt6_info *rt,
>
> 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 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct
> rt6_info *rt,
> 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 a9d3564caf49..33629f2a0f9d 100644
> --- 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,
> --
> 2.14.1.342.g6490525c54-goog
>
