Commit e1edc277 authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Linus Torvalds

linux/container_of.h: switch to static_assert

_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: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: default avatarMiguel Ojeda <ojeda@kernel.org>
Acked-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e52340de
...@@ -16,9 +16,9 @@ ...@@ -16,9 +16,9 @@
*/ */
#define container_of(ptr, type, member) ({ \ #define container_of(ptr, type, member) ({ \
void *__mptr = (void *)(ptr); \ void *__mptr = (void *)(ptr); \
BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ static_assert(__same_type(*(ptr), ((type *)0)->member) || \
!__same_type(*(ptr), void), \ __same_type(*(ptr), void), \
"pointer type mismatch in container_of()"); \ "pointer type mismatch in container_of()"); \
((type *)(__mptr - offsetof(type, member))); }) ((type *)(__mptr - offsetof(type, member))); })
/** /**
...@@ -31,9 +31,9 @@ ...@@ -31,9 +31,9 @@
*/ */
#define container_of_safe(ptr, type, member) ({ \ #define container_of_safe(ptr, type, member) ({ \
void *__mptr = (void *)(ptr); \ void *__mptr = (void *)(ptr); \
BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ static_assert(__same_type(*(ptr), ((type *)0)->member) || \
!__same_type(*(ptr), void), \ __same_type(*(ptr), void), \
"pointer type mismatch in container_of()"); \ "pointer type mismatch in container_of_safe()"); \
IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) : \ IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) : \
((type *)(__mptr - offsetof(type, member))); }) ((type *)(__mptr - offsetof(type, member))); })
......
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