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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
parentebda37c27d0c768947e9b058332d7ea798210cf8 (diff)
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')
-rw-r--r--include/net/dst.h48
-rw-r--r--include/net/sock.h13
2 files changed, 53 insertions, 8 deletions
diff --git a/include/net/dst.h b/include/net/dst.h
index aac5a5fcfda9..27207a13f2a6 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -168,6 +168,12 @@ static inline void dst_use(struct dst_entry *dst, unsigned long time)
dst->lastuse = time;
}
+static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
+{
+ dst->__use++;
+ dst->lastuse = time;
+}
+
static inline
struct dst_entry * dst_clone(struct dst_entry * dst)
{
@@ -177,11 +183,47 @@ struct dst_entry * dst_clone(struct dst_entry * dst)
}
extern void dst_release(struct dst_entry *dst);
+
+static inline void refdst_drop(unsigned long refdst)
+{
+ if (!(refdst & SKB_DST_NOREF))
+ dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
+}
+
+/**
+ * skb_dst_drop - drops skb dst
+ * @skb: buffer
+ *
+ * Drops dst reference count if a reference was taken.
+ */
static inline void skb_dst_drop(struct sk_buff *skb)
{
- if (skb->_skb_dst)
- dst_release(skb_dst(skb));
- skb->_skb_dst = 0UL;
+ if (skb->_skb_refdst) {
+ refdst_drop(skb->_skb_refdst);
+ skb->_skb_refdst = 0UL;
+ }
+}
+
+static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
+{
+ nskb->_skb_refdst = oskb->_skb_refdst;
+ if (!(nskb->_skb_refdst & SKB_DST_NOREF))
+ dst_clone(skb_dst(nskb));
+}
+
+/**
+ * skb_dst_force - makes sure skb dst is refcounted
+ * @skb: buffer
+ *
+ * If dst is not yet refcounted, let's do it
+ */
+static inline void skb_dst_force(struct sk_buff *skb)
+{
+ if (skb_dst_is_noref(skb)) {
+ WARN_ON(!rcu_read_lock_held());
+ skb->_skb_refdst &= ~SKB_DST_NOREF;
+ dst_clone(skb_dst(skb));
+ }
}
/* Children define the path of the packet through the
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;
}