linux-kernel - Re: [PATCH] erofs: Eliminate usage of uninitialized

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Message-ID: <20200615072521.GA25317@xiangao.remote.csb>
Date:   Mon, 15 Jun 2020 15:25:21 +0800
From:   Gao Xiang <hsiangkao@...hat.com>
To:     Jason Yan <yanaijie@...wei.com>
Cc:     xiang@...nel.org, chao@...nel.org, gregkh@...uxfoundation.org,
        linux-erofs@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH] erofs: Eliminate usage of uninitialized_var() macro

Hi Jason,

On Mon, Jun 15, 2020 at 12:01:41PM +0800, Jason Yan wrote:
> This is an effort to eliminate the uninitialized_var() macro[1].
> 
> The use of this macro is the wrong solution because it forces off ANY
> analysis by the compiler for a given variable. It even masks "unused
> variable" warnings.
> 
> Quoted from Linus[2]:
> 
> "It's a horrible thing to use, in that it adds extra cruft to the
> source code, and then shuts up a compiler warning (even the _reliable_
> warnings from gcc)."
> 
> The gcc option "-Wmaybe-uninitialized" has been disabled and this change
> will not produce any warnnings even with "make W=1".
> 
> [1] https://github.com/KSPP/linux/issues/81
> [2] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
> 
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Chao Yu <yuchao0@...wei.com>
> Signed-off-by: Jason Yan <yanaijie@...wei.com>
> ---

I'm fine with the patch since "-Wmaybe-uninitialized" has been disabled and
I've also asked Kees for it in private previously.

I still remembered that Kees sent out a treewide patch. Sorry about that
I don't catch up it... But what is wrong with the original patchset?

Thanks,
Gao Xiang