linux-kernel - Re: [PATCH v3 2/3] coccinelle: api: extend memdup_user rule with vmemdup

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Date:   Wed, 22 Jul 2020 07:50:49 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Julia Lawall <julia.lawall@...ia.fr>,
        Denis Efremov <efremov@...ux.com>,
        Coccinelle <cocci@...teme.lip6.fr>
Cc:     Gilles Muller <Gilles.Muller@...6.fr>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v3 2/3] coccinelle: api: extend memdup_user rule with
 vmemdup_user()

>>> +@...ends on patch@
>>> +expression from,to,size;
>>> +identifier l1,l2;
>>> +@@
>>> +
>>> +-  to = \(kvmalloc\|kvzalloc\)(size,\(GFP_KERNEL\|GFP_USER\));
>>> ++  to = 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 = \(kvmalloc@p\|kvzalloc@p\)(size,\(GFP_KERNEL\|GFP_USER\));
>>> +   if (to==NULL || ...) S1
>>> +   if (copy_from_user(to, from, size) != 0)
>>> +   S2
>>
>> * Can it be helpful to omit the SmPL asterisk functionality from
>>   the operation modes “org” and “report”?
>>
>> * Should the operation mode “context” work without an extra 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