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SubjectRe: [PATCH v2] dynamic_debug: Use address-of operator on section symbols
On Wed, Feb 19, 2020 at 10:13:20PM -0700, Nathan Chancellor wrote:
> Clang warns:
>
> ../lib/dynamic_debug.c:1034:24: warning: array comparison always
> evaluates to false [-Wtautological-compare]
> if (__start___verbose == __stop___verbose) {
> ^
> 1 warning generated.
>
> These are not true arrays, they are linker defined symbols, which are
> just addresses. Using the address of operator silences the warning and
> does not change the resulting assembly with either clang/ld.lld or
> gcc/ld (tested with diff + objdump -Dr).
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/894
> Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> v1 -> v2: https://lore.kernel.org/lkml/20200219045423.54190-5-natechancellor@gmail.com/
>
> * No longer a series because there is no prerequisite patch.
> * Use address-of operator instead of casting to unsigned long.
>
> lib/dynamic_debug.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index aae17d9522e5..8f199f403ab5 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -1031,7 +1031,7 @@ static int __init dynamic_debug_init(void)
> int n = 0, entries = 0, modct = 0;
> int verbose_bytes = 0;
>
> - if (__start___verbose == __stop___verbose) {
> + if (&__start___verbose == &__stop___verbose) {
> pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
> return 1;
> }
> --
> 2.25.1
>

Gentle ping for review/acceptance.

Cheers,
Nathan

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