From 35edd9103c84f2b37f63227d12765c38f30495c5 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Wed, 16 Nov 2011 23:51:05 -0500 Subject: [PATCH] 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 $ 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 --- include/linux/bug.h | 61 ++++++++++++++++++++++++++++++++++++++++++ include/linux/kernel.h | 61 ------------------------------------------ 2 files changed, 61 insertions(+), 61 deletions(-) diff --git a/include/linux/bug.h b/include/linux/bug.h index d276b5510c83..72961c39576a 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -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 diff --git a/include/linux/kernel.h b/include/linux/kernel.h index e8343422240a..5dba983b8d65 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -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__) -- 2.20.1