decnet: use correct RCU API to deref sk_dst_cache field

sock->sk_dst_cache is protected by RCU, therefore we should
use __sk_dst_get() to deref it once we lock the sock.

This fixes several sparse warnings.

Cc: linux-decnet-user@lists.sourceforge.net
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 7 insertions, 5 deletions

diff --git a/include/net/dn_route.h b/include/net/dn_route.h
index 4f7d6a182381..2e9d317c82dc 100644
--- a/include/net/dn_route.h
+++ b/include/net/dn_route.h
@@ -16,7 +16,7 @@
 *******************************************************************************/
 
 extern struct sk_buff *dn_alloc_skb(struct sock *sk, int size, gfp_t pri);
-extern int dn_route_output_sock(struct dst_entry **pprt, struct flowidn *, struct sock *sk, int flags);
+extern int dn_route_output_sock(struct dst_entry __rcu **pprt, struct flowidn *, struct sock *sk, int flags);
 extern int dn_cache_dump(struct sk_buff *skb, struct netlink_callback *cb);
 extern void dn_rt_cache_flush(int delay);
 
diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index 307c322d53bb..64d9843f9e04 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -909,6 +909,7 @@ static int __dn_connect(struct sock *sk, struct sockaddr_dn *addr, int addrlen,
         struct dn_scp *scp = DN_SK(sk);
         int err = -EISCONN;
         struct flowidn fld;
+        struct dst_entry *dst;
 
         if (sock->state == SS_CONNECTED)
                 goto out;
@@ -955,10 +956,11 @@ static int __dn_connect(struct sock *sk, struct sockaddr_dn *addr, int addrlen,
         fld.flowidn_proto = DNPROTO_NSP;
         if (dn_route_output_sock(&sk->sk_dst_cache, &fld, sk, flags) < 0)
                 goto out;
-        sk->sk_route_caps = sk->sk_dst_cache->dev->features;
+        dst = __sk_dst_get(sk);
+        sk->sk_route_caps = dst->dev->features;
         sock->state = SS_CONNECTING;
         scp->state = DN_CI;
-        scp->segsize_loc = dst_metric_advmss(sk->sk_dst_cache);
+        scp->segsize_loc = dst_metric_advmss(dst);
 
         dn_nsp_send_conninit(sk, NSP_CI);
         err = -EINPROGRESS;
diff --git a/net/decnet/dn_nsp_out.c b/net/decnet/dn_nsp_out.c
index 8a96047c7c94..1aaa51ebbda6 100644
--- a/net/decnet/dn_nsp_out.c
+++ b/net/decnet/dn_nsp_out.c
@@ -598,7 +598,7 @@ void dn_nsp_send_disc(struct sock *sk, unsigned char msgflg,
         if (reason == 0)
                 reason = le16_to_cpu(scp->discdata_out.opt_status);
 
-        dn_nsp_do_disc(sk, msgflg, reason, gfp, sk->sk_dst_cache, ddl,
+        dn_nsp_do_disc(sk, msgflg, reason, gfp, __sk_dst_get(sk), ddl,
                 scp->discdata_out.opt_data, scp->addrrem, scp->addrloc);
 }
 
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index b57419cc41a4..1550028fcd8e 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1282,7 +1282,7 @@ static int dn_route_output_key(struct dst_entry **pprt, struct flowidn *flp, int
         return err;
 }
 
-int dn_route_output_sock(struct dst_entry **pprt, struct flowidn *fl, struct sock *sk, int flags)
+int dn_route_output_sock(struct dst_entry __rcu **pprt, struct flowidn *fl, struct sock *sk, int flags)
 {
         int err;