Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

[deliverable/linux.git] / include / linux / skbuff.h

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 797cefb888fb075a9e6c458a0c3d05edfe5d3e35..15d0df9434667922894936216d17bf88120d60cc 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1981,6 +1981,30 @@ 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