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Subject: Re: [PATCH v3 2/3] coccinelle: api: extend memdup_user rule with
 vmemdup_user()
To:     Julia Lawall <julia.lawall@inria.fr>,
        Denis Efremov <efremov@linux.com>,
        Coccinelle <cocci@systeme.lip6.fr>
Cc:     Gilles Muller <Gilles.Muller@lip6.fr>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Nicolas Palix <nicolas.palix@imag.fr>,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
References: <e3d2ffb9-2a47-3d77-0501-9d48845435bd@web.de>
 <alpine.DEB.2.22.394.2007211158310.2487@hadrien>
From:   Markus Elfring <Markus.Elfring@web.de>
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Date:   Wed, 22 Jul 2020 07:50:49 +0200
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Sender: linux-kernel-owner@vger.kernel.org
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>>> +@depends on patch@
>>> +expression from,to,size;
>>> +identifier l1,l2;
>>> +@@
>>> +
>>> +-  to =3D \(kvmalloc\|kvzalloc\)(size,\(GFP_KERNEL\|GFP_USER\));
>>> ++  to =3D vmemdup_user(from,size);
>>
>> I propose to combine the desired adjustment with the previous SmPL rule
>> by using another disjunction.

How do you think about to check run time characteristics for
the following SmPL script sketches?

A)
@R1@
@@
// Change something

@R2@
@@
// Change another thing


B)
@Replacement_with_disjunction@
@@
(
// R1: Change something
|
// R2: Change another thing
)


>>> +@rv depends on !patch@
>>> +expression from,to,size;
>>> +position p;
>>> +statement S1,S2;
>>> +@@
>>> +
>>> +*  to =3D \(kvmalloc@p\|kvzalloc@p\)(size,\(GFP_KERNEL\|GFP_USER\));
>>> +   if (to=3D=3DNULL || ...) S1
>>> +   if (copy_from_user(to, from, size) !=3D 0)
>>> +   S2
>>
>> * Can it be helpful to omit the SmPL asterisk functionality from
>>   the operation modes =E2=80=9Corg=E2=80=9D and =E2=80=9Creport=E2=80=
=9D?
>>
>> * Should the operation mode =E2=80=9Ccontext=E2=80=9D work without an e=
xtra position metavariable?
>
> This is fine as is in all three aspects.

Is every technique from the Coccinelle software required for
each operation mode in such data processing approaches?

Regards,
Markus