linux-kernel - Re: [v5] coccinelle: semantic code search for missingput

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Date:   Sat, 16 Feb 2019 09:09:55 +0100
From:   Markus Elfring <Markus.Elfring@....de>
To:     Wen Yang <wen.yang99@....com.cn>
Cc:     Julia Lawall <julia.lawall@...6.fr>,
        Gilles Muller <Gilles.Muller@...6.fr>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Michal Marek <michal.lkml@...kovi.net>,
        Yi Wang <wang.yi59@....com.cn>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Wen Yang <yellowriver2010@...mail.com>,
        Cheng Shengyu <cheng.shengyu@....com.cn>,
        cocci@...teme.lip6.fr, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [v5] coccinelle: semantic code search for missingput_device()

> 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 “of_find_device_by_node”.

2. The source code search will be continued with …

> 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 “local” really sufficient when such a pointer
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 external 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 concerns
around a tool like “grep”.

>> 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 analysis
> and other functions.

This functionality will need further clarification.

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

I am curious on how this situation will evolve further.

Regards,
Markus