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>
This commit is contained in:
Eric Dumazet 2008-11-26 01:08:18 -08:00 committed by David S. Miller
parent dd24c00191
commit 7035560287

View File

@ -289,7 +289,11 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
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