From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Sat, 04 Apr 2015 17:12:43 +0000
Subject: Re: [PATCH 2/2] staging: emxx_udc: test returned value
Message-Id: <20150404171243.GY10964@mwanda>
List-Id: <kernel-janitors.vger.kernel.org>
References: <1428159570-19467-1-git-send-email-Julia.Lawall@lip6.fr>
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 <20150404160712.GA19278@kroah.com>
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To: Julia Lawall <julia.lawall@lip6.fr>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, devel@driverdev.osuosl.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org

On Sat, Apr 04, 2015 at 06:20:53PM +0200, Julia Lawall wrote:
> Couldn't one say:
> 
> x = NULL;
> y = &x->whatever;
> z = container_of(y, struct blah, whatever);
> 
> and end up with z being NULL?

That is crazy person code.  It looks deliberately wrong.  If we start
merging deliberate mistakes then we're already screwed.

I have a smatch check which warns on container_of() but I should update
it to not complain if it's the first struct member.  I have looked at
quite a few of these warnings and I worry that there are some places
where it relies on container_of() to be a no-op...  That's also crazy
but it's the kind of crazy that people do in real life.  :P

regards,
dan carpenter