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From: Markus Elfring <Markus.Elfring@web.de>
To: Julia Lawall <julia.lawall@lip6.fr>,
	Wen Yang <yellowriver2010@hotmail.com>
Cc: Michal Marek <michal.lkml@markovi.net>,
	kernel-janitors@vger.kernel.org,
	Nicolas Palix <nicolas.palix@imag.fr>,
	LKML <linux-kernel@vger.kernel.org>,
	Coccinelle <cocci@systeme.lip6.fr>,
	Cheng Shengyu <cheng.shengyu@zte.com.cn>,
	Wen Yang <wen.yang99@zte.com.cn>
Subject: Re: [Cocci] [v6] coccinelle: semantic code search for missing put_device()
Date: Sun, 17 Feb 2019 14:14:38 +0100
Message-ID: <52c07e7c-eec7-792b-0b03-b5cb46ddeab3@web.de> (raw)
In-Reply-To: <alpine.DEB.2.21.1902171350500.2444@hadrien>

>> …
>> +@search exists@
>> +local idexpression id;
>> +expression x,e,e1;
>> +position p1,p2;
>> …
>> +@@
>> +
>> +id = of_find_device_by_node@p1(x)
>> +... when != e = id
>> …
>>
>> Or:
>>
>> …
>> + ... when != id = e
>> …
>>
>>
>> Which SmPL specification will achieve the desired software behaviour?
>
> The desired behavior is to check whether the allocated value is saved in
> some other variable (typically a structure field) and thus it doesn't need
> to be freed just because the original local variable goes out of scope at
> the end of the function.

I find this description reasonable to some degree.

(I am unsure if a programmer would like to fiddle with return value storage
in a data structure member from a local variable.)


> when != e = id achieves this behavior.

I can not agree to this view completely because of the meaning that is connected
with these variable identifiers.

Both metavariables share the kind “expression”. So I can imagine
that there is an intersection for the source code match possibility.
But one was intentionally restricted to the kind “local idexpression” so far.

Which data element should not get reassigned here (before a corresponding
null pointer check)?

Regards,
Markus
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Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-16 16:05 [Cocci] [PATCH v6] " Wen Yang
2019-02-16 16:33 ` Julia Lawall
2019-02-16 18:39 ` [Cocci] [v6] " Markus Elfring
2019-02-17  2:32   ` [Cocci] 答复: " Wen Yang
2019-02-17  7:42     ` Markus Elfring
2019-02-17  9:50 ` [Cocci] [PATCH v6] " Markus Elfring
2019-02-17 11:37   ` Julia Lawall
2019-02-17 11:42     ` Markus Elfring
2019-02-17 11:48       ` Julia Lawall
2019-02-17 12:00         ` [Cocci] [v6] " Markus Elfring
2019-02-17 12:05           ` Julia Lawall
2019-02-17 12:20             ` Markus Elfring
2019-02-17 12:52               ` Julia Lawall
2019-02-17 13:14                 ` Markus Elfring [this message]
2019-02-18  3:22                   ` wen.yang99
2019-02-18  6:43                     ` Julia Lawall
2019-02-18  8:19                       ` Markus Elfring
2019-02-19  2:14                         ` wen.yang99
2019-02-19  7:04                           ` Julia Lawall
2019-02-19  8:12                             ` Markus Elfring
2019-02-19  8:29                           ` Markus Elfring
2019-02-19  9:09                             ` wen.yang99
2019-02-19  9:30                               ` Markus Elfring
2019-03-06 11:18                           ` Markus Elfring
2019-02-18 21:40                     ` Markus Elfring

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