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bug: consolidate BUILD_BUG_ON with other bug code 

The support for BUILD_BUG in linux/kernel.h predates the
addition of linux/bug.h -- with this chunk off separate,
you can run into situations where a person gets a compile
fail even when they've included linux/bug.h, like this:

    CC      lib/string.o
  lib/string.c: In function 'strlcat':
  lib/string.c:225:2: error: implicit declaration of function 'BUILD_BUG_ON'
  make[2]: *** [lib/string.o] Error 1
  $
  $ grep linux/bug.h lib/string.c
  #include <linux/bug.h>
  $

Since the above violates the principle of least surprise, move
the BUG chunks from kernel.h to bug.h so it is all together.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
This commit is contained in:
Paul Gortmaker 2011-11-16 23:51:05 -05:00
parent 187f1882b5
commit 35edd9103c
2 changed files with 61 additions and 61 deletions
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61
include/linux/bug.h
View File

@ -11,6 +11,67 @@ enum bug_trap_type {
struct pt_regs;
#ifdef __CHECKER__
#define BUILD_BUG_ON_NOT_POWER_OF_2(n)
#define BUILD_BUG_ON_ZERO(e) (0)
#define BUILD_BUG_ON_NULL(e) ((void*)0)
#define BUILD_BUG_ON(condition)
#define BUILD_BUG() (0)
#else /* __CHECKER__ */
/* Force a compilation error if a constant expression is not a power of 2 */
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
/* Force a compilation error if condition is true, but also produce a
result (of value 0 and type size_t), so the expression can be used
e.g. in a structure initializer (or where-ever else comma expressions
aren't permitted). */
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
/**
* BUILD_BUG_ON - break compile if a condition is true.
* @condition: the condition which the compiler should know is false.
*
* If you have some code which relies on certain constants being equal, or
* other compile-time-evaluated condition, you should use BUILD_BUG_ON to
* detect if someone changes it.
*
* The implementation uses gcc's reluctance to create a negative array, but
* gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
* to inline functions). So as a fallback we use the optimizer; if it can't
* prove the condition is false, it will cause a link error on the undefined
* "__build_bug_on_failed". This error message can be harder to track down
* though, hence the two different methods.
*/
#ifndef __OPTIMIZE__
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#else
extern int __build_bug_on_failed;
#define BUILD_BUG_ON(condition) \
do { \
((void)sizeof(char[1 - 2*!!(condition)])); \
if (condition) __build_bug_on_failed = 1; \
} while(0)
#endif
/**
* BUILD_BUG - break compile if used.
*
* If you have some code that you expect the compiler to eliminate at
* build time, you should use BUILD_BUG to detect if it is
* unexpectedly used.
*/
#define BUILD_BUG() \
do { \
extern void __build_bug_failed(void) \
__linktime_error("BUILD_BUG failed"); \
__build_bug_failed(); \
} while (0)
#endif /* __CHECKER__ */
#ifdef CONFIG_GENERIC_BUG
#include <asm-generic/bug.h>

61
include/linux/kernel.h
View File

@ -662,67 +662,6 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
#ifdef __CHECKER__
#define BUILD_BUG_ON_NOT_POWER_OF_2(n)
#define BUILD_BUG_ON_ZERO(e) (0)
#define BUILD_BUG_ON_NULL(e) ((void*)0)
#define BUILD_BUG_ON(condition)
#define BUILD_BUG() (0)
#else /* __CHECKER__ */
/* Force a compilation error if a constant expression is not a power of 2 */
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
/* Force a compilation error if condition is true, but also produce a
result (of value 0 and type size_t), so the expression can be used
e.g. in a structure initializer (or where-ever else comma expressions
aren't permitted). */
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
/**
* BUILD_BUG_ON - break compile if a condition is true.
* @condition: the condition which the compiler should know is false.
*
* If you have some code which relies on certain constants being equal, or
* other compile-time-evaluated condition, you should use BUILD_BUG_ON to
* detect if someone changes it.
*
* The implementation uses gcc's reluctance to create a negative array, but
* gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
* to inline functions). So as a fallback we use the optimizer; if it can't
* prove the condition is false, it will cause a link error on the undefined
* "__build_bug_on_failed". This error message can be harder to track down
* though, hence the two different methods.
*/
#ifndef __OPTIMIZE__
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#else
extern int __build_bug_on_failed;
#define BUILD_BUG_ON(condition) \
do { \
((void)sizeof(char[1 - 2*!!(condition)])); \
if (condition) __build_bug_on_failed = 1; \
} while(0)
#endif
/**
* BUILD_BUG - break compile if used.
*
* If you have some code that you expect the compiler to eliminate at
* build time, you should use BUILD_BUG to detect if it is
* unexpectedly used.
*/
#define BUILD_BUG() \
do { \
extern void __build_bug_failed(void) \
__linktime_error("BUILD_BUG failed"); \
__build_bug_failed(); \
} while (0)
#endif /* __CHECKER__ */
/* Trap pasters of __FUNCTION__ at compile-time */
#define __FUNCTION__ (__func__)