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e1edc277e6
_Static_assert() is evaluated already in the compiler's frontend, and
gives a somehat more to-the-point error, compared to the BUILD_BUG_ON
macro, which only fires after the optimizer has had a chance to
eliminate calls to functions marked with __attribute__((error)). In
theory, this might make builds a tiny bit faster.
There's also a little less gunk in the error message emitted:
lib/sort.c: In function `foo':
include/linux/build_bug.h:78:41: error: static assertion failed: "pointer type mismatch in container_of()"
78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
compared to
lib/sort.c: In function `foo':
include/linux/compiler_types.h:322:38: error: call to `__compiletime_assert_2' declared with attribute error: pointer type mismatch in container_of()
322 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
While at it, fix the copy-pasto in container_of_safe().
Link: https://lkml.kernel.org/r/20211015090530.2774079-1-linux@rasmusvillemoes.dk
Link: https://lore.kernel.org/lkml/20211014132331.GA4811@kernel.org/T/
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
40 lines
1.4 KiB
C
40 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_CONTAINER_OF_H
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#define _LINUX_CONTAINER_OF_H
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#include <linux/build_bug.h>
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#include <linux/err.h>
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#define typeof_member(T, m) typeof(((T*)0)->m)
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/**
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* container_of - cast a member of a structure out to the containing structure
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* @ptr: the pointer to the member.
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* @type: the type of the container struct this is embedded in.
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* @member: the name of the member within the struct.
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*
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*/
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#define container_of(ptr, type, member) ({ \
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void *__mptr = (void *)(ptr); \
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static_assert(__same_type(*(ptr), ((type *)0)->member) || \
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__same_type(*(ptr), void), \
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"pointer type mismatch in container_of()"); \
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((type *)(__mptr - offsetof(type, member))); })
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/**
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* container_of_safe - cast a member of a structure out to the containing structure
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* @ptr: the pointer to the member.
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* @type: the type of the container struct this is embedded in.
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* @member: the name of the member within the struct.
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*
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* If IS_ERR_OR_NULL(ptr), ptr is returned unchanged.
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*/
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#define container_of_safe(ptr, type, member) ({ \
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void *__mptr = (void *)(ptr); \
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static_assert(__same_type(*(ptr), ((type *)0)->member) || \
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__same_type(*(ptr), void), \
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"pointer type mismatch in container_of_safe()"); \
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IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) : \
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((type *)(__mptr - offsetof(type, member))); })
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#endif /* _LINUX_CONTAINER_OF_H */
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