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authorEric Dumazet <eric.dumazet@gmail.com>2010-05-11 23:19:48 (GMT)
committerDavid S. Miller <davem@davemloft.net>2010-05-18 00:18:50 (GMT)
commit7fee226ad2397b635e2fd565a59ca3ae08a164cd (patch)
tree0bcd26150ad74ec1a237109de87a3d214a07fc22 /net/core/sock.c
parentebda37c27d0c768947e9b058332d7ea798210cf8 (diff)
downloadlinux-fsl-qoriq-7fee226ad2397b635e2fd565a59ca3ae08a164cd.tar.xz
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 'net/core/sock.c')
-rw-r--r--net/core/sock.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/net/core/sock.c b/net/core/sock.c
index 63530a0..bf88a16 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -307,6 +307,11 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
*/
skb_len = skb->len;
+ /* we escape from rcu protected region, make sure we dont leak
+ * a norefcounted dst
+ */
+ skb_dst_force(skb);
+
spin_lock_irqsave(&list->lock, flags);
skb->dropcount = atomic_read(&sk->sk_drops);
__skb_queue_tail(list, skb);
@@ -1536,6 +1541,7 @@ static void __release_sock(struct sock *sk)
do {
struct sk_buff *next = skb->next;
+ WARN_ON_ONCE(skb_dst_is_noref(skb));
skb->next = NULL;
sk_backlog_rcv(sk, skb);