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-rw-r--r--include/linux/skbuff.h24
1 files changed, 24 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4ce9ff7086f4..d3fcd4591ce4 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1985,6 +1985,30 @@ static inline void skb_reserve(struct sk_buff *skb, int len)
skb->tail += len;
}
+/**
+ * skb_tailroom_reserve - adjust reserved_tailroom
+ * @skb: buffer to alter
+ * @mtu: maximum amount of headlen permitted
+ * @needed_tailroom: minimum amount of reserved_tailroom
+ *
+ * Set reserved_tailroom so that headlen can be as large as possible but
+ * not larger than mtu and tailroom cannot be smaller than
+ * needed_tailroom.
+ * The required headroom should already have been reserved before using
+ * this function.
+ */
+static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
+ unsigned int needed_tailroom)
+{
+ SKB_LINEAR_ASSERT(skb);
+ if (mtu < skb_tailroom(skb) - needed_tailroom)
+ /* use at most mtu */
+ skb->reserved_tailroom = skb_tailroom(skb) - mtu;
+ else
+ /* use up to all available space */
+ skb->reserved_tailroom = needed_tailroom;
+}
+
#define ENCAP_TYPE_ETHER 0
#define ENCAP_TYPE_IPPROTO 1