[PATCH] lib/checksum.c: fix endianess bug

[Arnd Bergmann]

The new generic checksum code has a small dependency on endianess and
worked only on big-endian systems. I could not find a nice efficient
way to express this, so I added an #ifdef. Using
'result += le16_to_cpu(*buff);' would have worked as well, but
would be slightly less efficient on big-endian systems and IMHO
would not be clearer.

Also fix a bug that prevents this from working on 64-bit machines.
If you have a 64-bit CPU and want to use the generic checksum
code, you should probably do some more optimizations anyway, but
at least the code should not break.

Reported-by: Mike Frysinger <vapier@xxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 lib/checksum.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/lib/checksum.c b/lib/checksum.c
index 12e5a1c..4a1c84a 100644
--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -71,7 +71,7 @@ static unsigned int do_csum(const unsigned char *buff, int len)
 		if (count) {
 			unsigned long carry = 0;
 			do {
-				unsigned long w = *(unsigned long *) buff;
+				unsigned long w = *(unsigned int *) buff;
 				count--;
 				buff += 4;
 				result += carry;
@@ -87,7 +87,11 @@ static unsigned int do_csum(const unsigned char *buff, int len)
 		}
 	}
 	if (len & 1)
+#ifdef __LITTLE_ENDIAN
+		result += *buff;
+#else
 		result += (*buff << 8);
+#endif
 	result = from32to16(result);
 	if (odd)
 		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
-- 
1.6.3.1

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