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Nathan Chancellor
cff8bf67f1
commit71945968d8upstream. A recent change to the optimization pipeline in LLVM reveals some fragility around the inlining of LoongArch's __percpu functions, which manifests as a BUILD_BUG() failure: In file included from kernel/sched/build_policy.c:17: In file included from include/linux/sched/cputime.h:5: In file included from include/linux/sched/signal.h:5: In file included from include/linux/rculist.h:11: In file included from include/linux/rcupdate.h:26: In file included from include/linux/irqflags.h:18: arch/loongarch/include/asm/percpu.h:97:3: error: call to '__compiletime_assert_51' declared with 'error' attribute: BUILD_BUG failed 97 | BUILD_BUG(); | ^ include/linux/build_bug.h:59:21: note: expanded from macro 'BUILD_BUG' 59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") | ^ include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG' 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) | ^ include/linux/compiler_types.h:425:2: note: expanded from macro 'compiletime_assert' 425 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) | ^ include/linux/compiler_types.h:413:2: note: expanded from macro '_compiletime_assert' 413 | __compiletime_assert(condition, msg, prefix, suffix) | ^ include/linux/compiler_types.h:406:4: note: expanded from macro '__compiletime_assert' 406 | prefix ## suffix(); \ | ^ <scratch space>:86:1: note: expanded from here 86 | __compiletime_assert_51 | ^ 1 error generated. If these functions are not inlined (which the compiler is free to do even with functions marked with the standard 'inline' keyword), the BUILD_BUG() in the default case cannot be eliminated since the compiler cannot prove it is never used, resulting in a build failure due to the error attribute. Mark these functions as __always_inline to guarantee inlining so that the BUILD_BUG() only triggers when the default case genuinely cannot be eliminated due to an unexpected size. Cc: <stable@vger.kernel.org> Closes: https://github.com/ClangBuiltLinux/linux/issues/1955 Fixes:46859ac8af("LoongArch: Add multi-processor (SMP) support") Link: https://github.com/llvm/llvm-project/commit/1a2e77cf9e11dbf56b5720c607313a566eebb16e Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.