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-rw-r--r--include/linux/skbuff.h40
1 files changed, 31 insertions, 9 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 93c27f7..a656cec 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1352,6 +1352,22 @@ static inline int skb_clone_writable(struct sk_buff *skb, int len)
skb_headroom(skb) + len <= skb->hdr_len;
}
+static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
+ int cloned)
+{
+ int delta = 0;
+
+ if (headroom < NET_SKB_PAD)
+ headroom = NET_SKB_PAD;
+ if (headroom > skb_headroom(skb))
+ delta = headroom - skb_headroom(skb);
+
+ if (delta || cloned)
+ return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
+ GFP_ATOMIC);
+ return 0;
+}
+
/**
* skb_cow - copy header of skb when it is required
* @skb: buffer to cow
@@ -1366,16 +1382,22 @@ static inline int skb_clone_writable(struct sk_buff *skb, int len)
*/
static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
{
- int delta = (headroom > NET_SKB_PAD ? headroom : NET_SKB_PAD) -
- skb_headroom(skb);
-
- if (delta < 0)
- delta = 0;
+ return __skb_cow(skb, headroom, skb_cloned(skb));
+}
- if (delta || skb_cloned(skb))
- return pskb_expand_head(skb, (delta + (NET_SKB_PAD-1)) &
- ~(NET_SKB_PAD-1), 0, GFP_ATOMIC);
- return 0;
+/**
+ * skb_cow_head - skb_cow but only making the head writable
+ * @skb: buffer to cow
+ * @headroom: needed headroom
+ *
+ * This function is identical to skb_cow except that we replace the
+ * skb_cloned check by skb_header_cloned. It should be used when
+ * you only need to push on some header and do not need to modify
+ * the data.
+ */
+static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
+{
+ return __skb_cow(skb, headroom, skb_header_cloned(skb));
}
/**
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