Date: Sat, 22 Jan 2022 19:36:40 GMT From: Vladimir Kondratyev <wulf@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: ef743744f0f4 - stable/13 - LinuxKPI: Use negative bit field size to trigger BUILD_BUG_ON_ZERO Message-ID: <202201221936.20MJaeUA000446@gitrepo.freebsd.org>
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The branch stable/13 has been updated by wulf: URL: https://cgit.FreeBSD.org/src/commit/?id=ef743744f0f4e06956fb785ed16cdc547758fefb commit ef743744f0f4e06956fb785ed16cdc547758fefb Author: Vladimir Kondratyev <wulf@FreeBSD.org> AuthorDate: 2021-12-25 18:42:15 +0000 Commit: Vladimir Kondratyev <wulf@FreeBSD.org> CommitDate: 2022-01-22 19:34:38 +0000 LinuxKPI: Use negative bit field size to trigger BUILD_BUG_ON_ZERO compile time assertion on non-NULL pointers. Tests conducted show that _Static_assert, negative array size method and current code does not handle pointers well enough. Bit field method solves this problem. This change is derrived from Linux implementation of BUILD_BUG_ON_ZERO. MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D33674 (cherry picked from commit 64dab63f3b3b6c6a1f8a92f43bed0aa28319d627) --- sys/compat/linuxkpi/common/include/linux/kernel.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/sys/compat/linuxkpi/common/include/linux/kernel.h b/sys/compat/linuxkpi/common/include/linux/kernel.h index 75e274205259..58581ebe9101 100644 --- a/sys/compat/linuxkpi/common/include/linux/kernel.h +++ b/sys/compat/linuxkpi/common/include/linux/kernel.h @@ -109,9 +109,7 @@ #define BUILD_BUG_ON_MSG(x, msg) BUILD_BUG_ON(x) #define BUILD_BUG_ON_NOT_POWER_OF_2(x) BUILD_BUG_ON(!powerof2(x)) #define BUILD_BUG_ON_INVALID(expr) while (0) { (void)(expr); } - -extern const volatile int lkpi_build_bug_on_zero; -#define BUILD_BUG_ON_ZERO(x) ((x) ? lkpi_build_bug_on_zero : 0) +#define BUILD_BUG_ON_ZERO(x) ((int)sizeof(struct { int:-((x) != 0); })) #define BUG() panic("BUG at %s:%d", __FILE__, __LINE__) #define BUG_ON(cond) do { \
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