net: cleanup and document skb fclone layout
Lets use a proper structure to clearly document and implement
skb fast clones.
Then, we might experiment more easily alternative layouts.
This patch adds a new skb_fclone_busy() helper, used by tcp and xfrm,
to stop leaking of implementation details.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 262efdb..d8f7d74 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -781,6 +781,31 @@
int *errcode,
gfp_t gfp_mask);
+/* Layout of fast clones : [skb1][skb2][fclone_ref] */
+struct sk_buff_fclones {
+ struct sk_buff skb1;
+
+ struct sk_buff skb2;
+
+ atomic_t fclone_ref;
+};
+
+/**
+ * skb_fclone_busy - check if fclone is busy
+ * @skb: buffer
+ *
+ * Returns true is skb is a fast clone, and its clone is not freed.
+ */
+static inline bool skb_fclone_busy(const struct sk_buff *skb)
+{
+ const struct sk_buff_fclones *fclones;
+
+ fclones = container_of(skb, struct sk_buff_fclones, skb1);
+
+ return skb->fclone == SKB_FCLONE_ORIG &&
+ fclones->skb2.fclone == SKB_FCLONE_CLONE;
+}
+
static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
gfp_t priority)
{