[PATCH v2] net: check for refcount if pop a stacked dst_entry

Steffen Klassert
2010-06-04T11:58:12Z

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>
---
include/net/dst.h | 6 +++---
net/xfrm/xfrm_output.c | 4 ++--
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/dst.h b/include/net/dst.h
index 612069b..81d1413 100644
--- 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
--- 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));

--
1.5.6.5