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-rw-r--r--include/linux/skbuff.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6b6bd42d6134..07f9ccd28654 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2805,6 +2805,23 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb,
unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
+static inline void skb_postpush_rcsum(struct sk_buff *skb,
+ const void *start, unsigned int len)
+{
+ /* For performing the reverse operation to skb_postpull_rcsum(),
+ * we can instead of ...
+ *
+ * skb->csum = csum_add(skb->csum, csum_partial(start, len, 0));
+ *
+ * ... just use this equivalent version here to save a few
+ * instructions. Feeding csum of 0 in csum_partial() and later
+ * on adding skb->csum is equivalent to feed skb->csum in the
+ * first place.
+ */
+ if (skb->ip_summed == CHECKSUM_COMPLETE)
+ skb->csum = csum_partial(start, len, skb->csum);
+}
+
/**
* pskb_trim_rcsum - trim received skb and update checksum
* @skb: buffer to trim