3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: karl beldan <[email protected]>

commit 150ae0e94634714b23919f0c333fee28a5b199d5 upstream.

The carry from the 64->32bits folding was dropped, e.g with:
saddr=0xFFFFFFFF daddr=0xFF0000FF len=0xFFFF proto=0 sum=1,
csum_tcpudp_nofold returned 0 instead of 1.

Signed-off-by: Karl Beldan <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Mike Frysinger <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 lib/checksum.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -47,6 +47,15 @@ static inline unsigned short from32to16(
        return x;
 }
 
+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;
+}
+
 static unsigned int do_csum(const unsigned char *buff, int len)
 {
        int odd;
@@ -195,8 +204,7 @@ __wsum csum_tcpudp_nofold(__be32 saddr,
 #else
        s += (proto + len) << 8;
 #endif
-       s += (s >> 32);
-       return (__force __wsum)s;
+       return (__force __wsum)from64to32(s);
 }
 EXPORT_SYMBOL(csum_tcpudp_nofold);
 #endif


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