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Subject: Re: [v5] coccinelle: semantic code search for missingput_device()
Cc:     Julia Lawall <julia.lawall@lip6.fr>,
        Gilles Muller <Gilles.Muller@lip6.fr>,
        Nicolas Palix <nicolas.palix@imag.fr>,
        Michal Marek <michal.lkml@markovi.net>,
        Yi Wang <wang.yi59@zte.com.cn>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Wen Yang <yellowriver2010@hotmail.com>,
        Cheng Shengyu <cheng.shengyu@zte.com.cn>,
        cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org
References: <201902161504357846572@zte.com.cn>
From:   Markus Elfring <Markus.Elfring@web.de>
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To:     Wen Yang <wen.yang99@zte.com.cn>
Message-ID: <10281c5d-8b32-0a02-17ae-20bf86f8dc65@web.de>
Date:   Sat, 16 Feb 2019 09:09:55 +0100
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Sender: linux-kernel-owner@vger.kernel.org
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> Thanks, We will change it to something like this:
> In a function, for a local variable obtained by of_find_device_by_node()

How do you think about another wording approach?

1. Precondition:
   It will be checked where the return value is stored from
   a call of the function =E2=80=9Cof_find_device_by_node=E2=80=9D.

2. The source code search will be continued with =E2=80=A6


> Thank you, but a local variable is necessary.

Would you like to take additional storage possibilities for a safer
analysis approach into account?

Is the restriction =E2=80=9Clocal=E2=80=9D really sufficient when such a p=
ointer
could be copied to other variables?


>> Can it happen that on other function will perform the desired reference=
 release?
>
> Thanks.
> Because the information of this local variable is not passed to the exte=
rnal function,
> this situation does not exist.

Will copied pointers matter here?


> But it's over 80 characters.

Long string literals can be accepted because of error message search conce=
rns
around a tool like =E2=80=9Cgrep=E2=80=9D.


>> Will any more advanced error diagnostics be eventually developed?
>
> Hello, we are just doing the practical work in this field.

Are you aware of additional software design options from computer science
and existing analysis tools?


> We also hope that it can support cross-function/cross-file/data stream a=
nalysis
> and other functions.

This functionality will need further clarification.


> We are also analyzing the principle and code implementation of coccinell=
e,
> hoping to contribute a little.

I am curious on how this situation will evolve further.

Regards,
Markus