lib/checksum.c: fix endianess bug (32a9ff9c) · Commits · 戴 / test

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>

lib/checksum.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -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);

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