dst: no need to take reference on DST_NOCACHE dsts

Since commit f8864972126899 ("ipv4: fix dst race in sk_dst_get()")
DST_NOCACHE dst_entries get freed by RCU. So there is no need to get a
reference on them when we are in rcu protected sections.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Reviewed-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 21 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index e9281b5b7f59..ef64cec42804 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -717,9 +717,6 @@ static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
 	skb->_skb_refdst = (unsigned long)dst;
 }
 
-void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
-			 bool force);
-
 /**
  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
  * @skb: buffer
@@ -732,24 +729,8 @@ void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,
  */
 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
 {
-	__skb_dst_set_noref(skb, dst, false);
-}
-
-/**
- * skb_dst_set_noref_force - sets skb dst, without taking reference
- * @skb: buffer
- * @dst: dst entry
- *
- * Sets skb dst, assuming a reference was not taken on dst.
- * No reference is taken and no dst_release will be called. While for
- * cached dsts deferred reclaim is a basic feature, for entries that are
- * not cached it is caller's job to guarantee that last dst_release for
- * provided dst happens when nobody uses it, eg. after a RCU grace period.
- */
-static inline void skb_dst_set_noref_force(struct sk_buff *skb,
-					   struct dst_entry *dst)
-{
-	__skb_dst_set_noref(skb, dst, true);
+	WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
+	skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
 }
 
 /**