[PATCH Yakkety SRU] powerpc/64: Fix checksum folding in csum_add()

[Tim Gardner]

From: Shile Zhang <shile.zhang at nokia.com>

BugLink: http://bugs.launchpad.net/bugs/1670247

Paul's patch to fix checksum folding, commit b492f7e4e07a ("powerpc/64:
Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold")
missed a case in csum_add(). Fix it.

Signed-off-by: Shile Zhang <shile.zhang at nokia.com>
Acked-by: Paul Mackerras <paulus at ozlabs.org>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
(cherry picked from commit 6ad966d7303b70165228dba1ee8da1a05c10eefe)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 arch/powerpc/include/asm/checksum.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/checksum.h b/arch/powerpc/include/asm/checksum.h
index 1e8fceb..a67bb09 100644
--- a/arch/powerpc/include/asm/checksum.h
+++ b/arch/powerpc/include/asm/checksum.h
@@ -100,7 +100,7 @@ static inline __wsum csum_add(__wsum csum, __wsum addend)
 
 #ifdef __powerpc64__
 	res += (__force u64)addend;
-	return (__force __wsum)((u32)res + (res >> 32));
+	return (__force __wsum) from64to32(res);
 #else
 	asm("addc %0,%0,%1;"
 	    "addze %0,%0;"
-- 
2.7.4