lib/checksum.c: fix endianess bug

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@gentoo.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 9 insertions, 1 deletions

diff --git a/lib/checksum.c b/lib/checksum.c
index 12e5a1c91cda..b2e2fd468461 100644
--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -55,7 +55,11 @@ static unsigned int do_csum(const unsigned char *buff, int len)
                 goto out;
         odd = 1 & (unsigned long) buff;
         if (odd) {
+#ifdef __LITTLE_ENDIAN
                 result = *buff;
+#else
+                result += (*buff << 8);
+#endif
                 len--;
                 buff++;
         }
@@ -71,7 +75,7 @@ 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 +91,11 @@ 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);