1 files changed, 10 insertions, 2 deletions

diff --git a/lib/checksum.c b/lib/checksum.c
index 129775eb6de6..8b39e86dbab5 100644
--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -181,6 +181,15 @@ csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
 EXPORT_SYMBOL(csum_partial_copy);
 
 #ifndef csum_tcpudp_nofold
+static inline u32 from64to32(u64 x)
+{
+        /* add up 32-bit and 32-bit for 32+c bit */
+        x = (x & 0xffffffff) + (x >> 32);
+        /* add up carry.. */
+        x = (x & 0xffffffff) + (x >> 32);
+        return (u32)x;
+}
+
 __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
                         unsigned short len,
                         unsigned short proto,
@@ -195,8 +204,7 @@ __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 #else
         s += (proto + len) << 8;
 #endif
-        s += (s >> 32);
-        return (__force __wsum)s;
+        return (__force __wsum)from64to32(s);
 }
 EXPORT_SYMBOL(csum_tcpudp_nofold);
 #endif