linux-kernel - Re: [PATCH 09/10] treewide: Remove uninitialized

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Message-ID: <20200604132306.GO6578@ziepe.ca>
Date:   Thu, 4 Jun 2020 10:23:06 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Joe Perches <joe@...ches.com>,
        Andy Whitcroft <apw@...onical.com>, x86@...nel.org,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        b43-dev@...ts.infradead.org, netdev@...r.kernel.org,
        linux-wireless@...r.kernel.org, linux-ide@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-mm@...ck.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH 09/10] treewide: Remove uninitialized_var() usage

On Wed, Jun 03, 2020 at 04:32:02PM -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.
> 
> I preparation for removing[2] the[3] macro[4], remove all remaining
> needless uses with the following script:
> 
> git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
> 	xargs perl -pi -e \
> 		's/\buninitialized_var\(([^\)]+)\)/\1/g;
> 		 s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'
> 
> drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
> pathological white-space.
> 
> No outstanding warnings were found building allmodconfig with GCC 9.3.0
> for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
> alpha, and m68k.

At least in the infiniband part I'm confident that old gcc versions
will print warnings after this patch.

As the warnings are wrong, do we care? Should old gcc maybe just -Wno-
the warning?

Otherwise the IB bits look ok to me

Acked-by: Jason Gunthorpe <jgg@...lanox.com>

Jason