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-rw-r--r--include/net/checksum.h16
1 files changed, 16 insertions, 0 deletions
diff --git a/include/net/checksum.h b/include/net/checksum.h
index 6465bae80a4f..e339a9513e29 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -151,4 +151,20 @@ static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
(__force __be32)to, pseudohdr);
}
+static inline __wsum remcsum_adjust(void *ptr, __wsum csum,
+ int start, int offset)
+{
+ __sum16 *psum = (__sum16 *)(ptr + offset);
+ __wsum delta;
+
+ /* Subtract out checksum up to start */
+ csum = csum_sub(csum, csum_partial(ptr, start, 0));
+
+ /* Set derived checksum in packet */
+ delta = csum_sub(csum_fold(csum), *psum);
+ *psum = csum_fold(csum);
+
+ return delta;
+}
+
#endif