Re: [PATCH 00/10] Remove uninitialized_var() macro

From: Sedat Dilek <sedat.dilek@gmail.com>
To: Nathan Chancellor <natechancellor@gmail.com>
Cc: Kees Cook <keescook@chromium.org>,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Joe Perches <joe@perches.com>, Andy Whitcroft <apw@canonical.com>,
	x86@kernel.org, drbd-dev@lists.linbit.com,
	linux-block@vger.kernel.org, b43-dev@lists.infradead.org,
	netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	linux-ide@vger.kernel.org, linux-clk@vger.kernel.org,
	linux-spi@vger.kernel.org, linux-mm@kvack.org,
	Clang-Built-Linux ML <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH 00/10] Remove uninitialized_var() macro
Date: Thu, 4 Jun 2020 09:26:58 +0200	[thread overview]
Message-ID: <CA+icZUU4Re5g3rRJ=WF3_KiCEc3CUmbH_PibTunuK_E1QskEjQ@mail.gmail.com> (raw)
In-Reply-To: <20200604033347.GA3962068@ubuntu-n2-xlarge-x86>

On Thu, Jun 4, 2020 at 5:33 AM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Wed, Jun 03, 2020 at 04:31:53PM -0700, Kees Cook wrote:
> > Using uninitialized_var() is dangerous as it papers over real bugs[1]
> > (or can in the future), and suppresses unrelated compiler warnings
> > (e.g. "unused variable"). If the compiler thinks it is uninitialized,
> > either simply initialize the variable or make compiler changes.
> >
> > As recommended[2] by[3] Linus[4], remove the macro.
> >
> > Most of the 300 uses don't cause any warnings on gcc 9.3.0, so they're in
> > a single treewide commit in this series. A few others needed to actually
> > get cleaned up, and I broke those out into individual patches.
> >
> > -Kees
> >
> > [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> > [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> > [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> > [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
> >
> > Kees Cook (10):
> >   x86/mm/numa: Remove uninitialized_var() usage
> >   drbd: Remove uninitialized_var() usage
> >   b43: Remove uninitialized_var() usage
> >   rtlwifi: rtl8192cu: Remove uninitialized_var() usage
> >   ide: Remove uninitialized_var() usage
> >   clk: st: Remove uninitialized_var() usage
> >   spi: davinci: Remove uninitialized_var() usage
> >   checkpatch: Remove awareness of uninitialized_var() macro
> >   treewide: Remove uninitialized_var() usage
> >   compiler: Remove uninitialized_var() macro
>
> I applied all of these on top of cb8e59cc8720 and ran a variety of
> builds with clang for arm32, arm64, mips, powerpc, s390, and x86_64 [1]
> and only saw one warning pop up (which was about a variable being
> unused, commented on patch 9 about it). No warnings about uninitialized
> variables came up; clang's -Wuninitialized was not impacted by
> 78a5255ffb6a ("Stop the ad-hoc games with -Wno-maybe-initialized") so it
> should have caught anything egregious.
>
> [1]: https://github.com/nathanchance/llvm-kernel-testing
>
> For the series, consider it:
>
> Tested-by: Nathan Chancellor <natechancellor@gmail.com> [build]
>

Hi Kees,

I tried with updated version (checkpatch) of your tree and see no
(new) warnings in my build-log.

Feel free to add my...

Tested-by: Sedat Dilek <sedat.dilek@gmail.com>

Thanks.

Regards,
- Sedat -