Re: [PATCH 0/6] Silence some instances of -Wtautological-compare and enable globally

Andrew Morton
2020-04-21T04:03:34Z

On Tue, 18 Feb 2020 21:54:17 -0700 Nathan Chancellor <natechancellor@gmail.com> wrote:

> Hi everyone,
>
> This patch series aims to silence some instances of clang's
> -Wtautological-compare that are not problematic and enable it globally
> for the kernel because it has a bunch of subwarnings that can find real
> bugs in the kernel such as
> https://lore.kernel.org/lkml/20200116222658.5285-1-natechancellor@gmail.com/
> and https://bugs.llvm.org/show_bug.cgi?id=42666, which was specifically
> requested by Dmitry.
>
> The first patch adds a macro that casts the section variables to
> unsigned long (uintptr_t), which silences the warning and adds
> documentation.
>
> Patches two through four silence the warning in the places I have
> noticed it across all of my builds with -Werror, including arm, arm64,
> and x86_64 defconfig/allmodconfig/allyesconfig. There might still be
> more lurking but those will have to be teased out over time.
>
> Patch six finally enables the warning, while leaving one of the
> subwarnings disabled because it is rather noisy and somewhat pointless
> for the kernel, where core kernel code is expected to build and run with
> many different configurations where variable types can be different
> sizes.
>

For some reason none of these patches apply. Not sure why - prehaps
something in the diff headers.

Anyway, the kmemleak.c code has recently changed in ways which impact
these patches. Please take a look at that, redo, retest and resend?