Re: [PATCH v2] LLVMLinux: Remove warning about returning an uninitialized variable

From: Sam Ravnborg
Date: Sat Mar 22 2014 - 12:22:03 EST


On Sat, Mar 22, 2014 at 08:48:19AM -0700, behanw@xxxxxxxxxxxxxxxxxx wrote:
> From: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
>
> Fix uninitialized return code in default case in cmpxchg-local.h
>
> This patch fixes the code to prevent an uninitialized return value that is detected
> when compiling with clang. The bug produces numerous warnings when compiling the
> Linux kernel with clang.
>
> Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Mark Charlebois <charlebm@xxxxxxxxx>
> ---
> include/asm-generic/cmpxchg-local.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h
> index d8d4c89..9112111 100644
> --- a/include/asm-generic/cmpxchg-local.h
> +++ b/include/asm-generic/cmpxchg-local.h
> @@ -41,6 +41,7 @@ static inline unsigned long __cmpxchg_local_generic(volatile void *ptr,
> break;
> default:
> wrong_size_cmpxchg(ptr);
> + __builtin_unreachable();

It is unreachable() - see compiler.h

Sam
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