linux/include
Roland Dreier cc8ef6eb21 kernel.h: add BUILD_BUG_ON_NOT_POWER_OF_2()
Add BUILD_BUG_ON_NOT_POWER_OF_2()

When code relies on a constant being a power of 2:

	#define FOO	512	/* must be a power of 2 */

it would be nice to be able to do:

	BUILD_BUG_ON(!is_power_of_2(FOO));

However applying an inline function does not result in a compile-time
constant that can be used with BUILD_BUG_ON(), so trying that gives
results in:

	error: bit-field '<anonymous>' width not an integer constant

As suggested by akpm, rather than monkeying around with is_power_of_2()
and risking gcc warts about constant expressions, just create a macro
BUILD_BUG_ON_NOT_POWER_OF_2() to encapsulate this common requirement.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: David Dillow <dave@thedillows.org>
Cc: "Robert P. J. Day" <rpjday@crashcourse.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-16 12:15:39 -08:00
..
acpi ACPI: processor: remove _PDC object list from struct acpi_processor 2009-12-22 03:35:16 -05:00
asm-generic fix up O_SYNC comments 2009-12-17 11:03:24 -05:00
crypto
drm Merge branch 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2010-01-11 09:46:20 -08:00
keys
linux kernel.h: add BUILD_BUG_ON_NOT_POWER_OF_2() 2010-01-16 12:15:39 -08:00
math-emu
media V4L/DVB (13670): soc-camera: Add mt9t112 camera driver 2009-12-16 09:27:41 -02:00
mtd
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2010-01-14 08:36:15 -08:00
pcmcia pcmcia: CodingStyle fixes 2009-12-07 22:23:40 +01:00
rdma Merge branches 'amso1100', 'cma', 'cxgb3', 'ehca', 'ipath', 'ipoib', 'iser', 'misc', 'mlx4' and 'nes' into for-next 2009-12-15 23:39:25 -08:00
rxrpc
scsi libsrp: fix compile failure 2009-12-30 12:23:27 -08:00
sound Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
trace tracing: Fix sign fields in ftrace_define_fields_##call() 2009-12-30 10:27:06 -05:00
video Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6 2009-12-16 10:29:52 -08:00
xen
Kbuild