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authorEric Dumazet <eric.dumazet@gmail.com>2010-05-11 23:19:48 +0000
committerDavid S. Miller <davem@davemloft.net>2010-05-17 17:18:50 -0700
commit7fee226ad2397b635e2fd565a59ca3ae08a164cd (patch)
tree0bcd26150ad74ec1a237109de87a3d214a07fc22 /include/net/sock.h
parentebda37c27d0c768947e9b058332d7ea798210cf8 (diff)
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net: add a noref bit on skb dst
Use low order bit of skb->_skb_dst to tell dst is not refcounted. Change _skb_dst to _skb_refdst to make sure all uses are catched. skb_dst() returns the dst, regardless of noref bit set or not, but with a lockdep check to make sure a noref dst is not given if current user is not rcu protected. New skb_dst_set_noref() helper to set an notrefcounted dst on a skb. (with lockdep check) skb_dst_drop() drops a reference only if skb dst was refcounted. skb_dst_force() helper is used to force a refcount on dst, when skb is queued and not anymore RCU protected. Use skb_dst_force() in __sk_add_backlog(), __dev_xmit_skb() if !IFF_XMIT_DST_RELEASE or skb enqueued on qdisc queue, in sock_queue_rcv_skb(), in __nf_queue(). Use skb_dst_force() in dev_requeue_skb(). Note: dst_use_noref() still dirties dst, we might transform it later to do one dirtying per jiffies. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/sock.h')
-rw-r--r--include/net/sock.h13
1 files changed, 8 insertions, 5 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index aed16eb9db4b..5697caf8cc76 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -600,12 +600,15 @@ static inline int sk_stream_memory_free(struct sock *sk)
/* OOB backlog add */
static inline void __sk_add_backlog(struct sock *sk, struct sk_buff *skb)
{
- if (!sk->sk_backlog.tail) {
- sk->sk_backlog.head = sk->sk_backlog.tail = skb;
- } else {
+ /* dont let skb dst not refcounted, we are going to leave rcu lock */
+ skb_dst_force(skb);
+
+ if (!sk->sk_backlog.tail)
+ sk->sk_backlog.head = skb;
+ else
sk->sk_backlog.tail->next = skb;
- sk->sk_backlog.tail = skb;
- }
+
+ sk->sk_backlog.tail = skb;
skb->next = NULL;
}