On 2010-03-11, at 15:11, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
+static int __init fcntl_init(void)
{
+ /* please add new bits here to ensure allocation uniqueness */
+ BUILD_BUG_ON(17 != HWEIGHT32(
+ O_RDONLY | O_WRONLY | O_RDWR |
+ O_CREAT | O_EXCL | O_NOCTTY |
+ O_TRUNC | O_APPEND | O_NONBLOCK |
+ __O_SYNC | O_DSYNC | FASYNC |
+ O_DIRECT | O_LARGEFILE | O_DIRECTORY |
+ O_NOFOLLOW | O_NOATIME | O_CLOEXEC
+ ));
It's non-obvious why there are 18 flags listed here, but the hweight
is only 17? Presumably this is because O_RDONLY has value 0, but that
should at least be
listed in a comment, or the test could be written more explicitly, like:
BUILD_BUG_ON(18 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
...
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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