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Subject: Re: [3/3] Coccinelle: pci_free_consistent: Extend when constraints
 for two SmPL ellipses
To:     Julia Lawall <julia.lawall@lip6.fr>
Cc:     Coccinelle <cocci@systeme.lip6.fr>,
        LKML <linux-kernel@vger.kernel.org>,
        Cheng Shengyu <cheng.shengyu@zte.com.cn>,
        Gilles Muller <Gilles.Muller@lip6.fr>,
        Ma Jiang <ma.jiang@zte.com.cn>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Nicolas Palix <nicolas.palix@imag.fr>,
        Wen Yang <wen.yang99@zte.com.cn>,
        Yi Wang <wang.yi59@zte.com.cn>
References: <201905151043340243098@zte.com.cn>
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From:   Markus Elfring <Markus.Elfring@web.de>
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Date:   Wed, 15 May 2019 13:18:29 +0200
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Am 15.05.19 um 12:19 schrieb Julia Lawall:
>
>
> On Wed, 15 May 2019, Markus Elfring wrote:
>
>>>>> On the other hand, I do care about causing false negatives.
>>>>
>>>> Do you find the missing warning after the addition of such an exclusi=
on
>>>> specification interesting?
>>>
>>> I already suggested how to improve the code.
>>
>> I find that the idea =E2=80=9Ce2->fld=E2=80=9D needs further clarificat=
ion.
>> Such a SmPL specification will be resolved also to an expression,
>> won't it?
>
> Saving in a local variable doesn't impact the need to free the object.

I suggest to reconsider this view.

Would we like to introduce additional case distinctions for the handling
of reassignments to local variables (as shown in Wen's test case)?


> A field is the most obvious case where the object may not need freeing.

A corresponding resource release should probably be performed by
an other function then.


> But there are many expressions that e2->fld will not match.

Data structure members can eventually belong also to a local variable.
Would they become relevant for further SmPL exclusion specifications?

Regards,
Markus