net: check for refcount if pop a stacked dst_entry

xfrm triggers a warning if dst_pop() drops a refcount
on a noref dst. This patch changes dst_pop() to
skb_dst_pop(). skb_dst_pop() drops the refcnt only
on a refcounted dst. Also we don't clone the child
dst_entry, so it is not refcounted and we can use
skb_dst_set_noref() in xfrm_output_one().

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/dst.h b/include/net/dst.h
index 612069b..81d1413 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -250,11 +250,11 @@ static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
  * Linux networking.  Thus, destinations are stackable.
  */
 
-static inline struct dst_entry *dst_pop(struct dst_entry *dst)
+static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 {
-       struct dst_entry *child = dst_clone(dst->child);
+       struct dst_entry *child = skb_dst(skb)->child;
 
-       dst_release(dst);
+       skb_dst_drop(skb);
        return child;
 }
 

diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 6a32915..a3cca0a 100644 (file)
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -95,13 +95,13 @@ resume:
                        goto error_nolock;
                }
 
-               dst = dst_pop(dst);
+               dst = skb_dst_pop(skb);
                if (!dst) {
                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
                        err = -EHOSTUNREACH;
                        goto error_nolock;
                }
-               skb_dst_set(skb, dst);
+               skb_dst_set_noref(skb, dst);
                x = dst->xfrm;
        } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));