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| author | Arnd Bergmann <arnd@arndb.de> | 2009-06-19 10:41:19 +0200 |
|---|---|---|
| committer | Arnd Bergmann <arnd@arndb.de> | 2009-06-19 14:58:13 +0200 |
| commit | 32a9ff9cc55b42543a84bca90b070df92af72671 (patch) | |
| tree | ce4d38741f8b78f5e4f193f5032846743e76b183 /lib/checksum.c | |
| parent | fcec9bf12442d0cd50d6cee125d168cfc3f37c5e (diff) | |
| download | lwn-32a9ff9cc55b42543a84bca90b070df92af72671.tar.gz lwn-32a9ff9cc55b42543a84bca90b070df92af72671.zip | |
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>
Diffstat (limited to 'lib/checksum.c')
| -rw-r--r-- | lib/checksum.c | 10 |
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); |