net: release skb->dst in sock_queue_rcv_skb()
When queuing a skb to sk->sk_receive_queue, we can release its dst,
not anymore needed. Since current cpu did the dst_hold(), refcount is
probably still hot int this cpu caches.
This avoids readers to access the original dst to decrement its
refcount, possibly a long time after packet reception. This should
speedup UDP and RAW receive path.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index 7a081b6..b287645 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -289,7 +289,11 @@
skb->dev = NULL;
skb_set_owner_r(skb, sk);
-
+ /*
+ * release dst right now while its hot
+ */
+ dst_release(skb->dst);
+ skb->dst = NULL;
/* Cache the SKB length before we tack it onto the receive
* queue. Once it is added it no longer belongs to us and
* may be freed by other threads of control pulling packets
