linux-kernel - Re: [PATCH 2/2] Coccinelle: extend memdup_user rule with vmemdup

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Date:   Sun, 31 May 2020 20:43:44 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Denis Efremov <efremov@...ux.com>,
        Gilles Muller <Gilles.Muller@...6.fr>,
        Julia Lawall <Julia.Lawall@...6.fr>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Coccinelle <cocci@...teme.lip6.fr>
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        Joe Perches <joe@...ches.com>
Subject: Re: [PATCH 2/2] Coccinelle: extend memdup_user rule with
 vmemdup_user()

> Add vmemdup_user() transformations to the memdup_user.cocci rule.
> Commit 50fd2f298bef ("new primitive: vmemdup_user()") introduced
> vmemdup_user(). The function uses kvmalloc with GPF_USER flag.

Such a software evolution is also interesting.


> +@...ends on patch@


> +-  to = \(kvmalloc\|kvzalloc\)(size,\(GFP_KERNEL\|GFP_USER\));
> ++  to = vmemdup_user(from,size);

How do you think about to achieve the desired data processing by the application
of a SmPL disjunction like the following?

 to =
(
-     \( kmalloc \| kzalloc \) (size, \( GFP_KERNEL \| GFP_USER \))
+     memdup_user(from, size)
|
-     \( kvmalloc \| kvzalloc \) (size, \( GFP_KERNEL \| GFP_USER \))
+     vmemdup_user(from, size)
)
 ;


Unfortunately, the Coccinelle software does not like the following
SmPL code variant so far.

 to =
(
-     \( kmalloc \| kzalloc \)
+     memdup_user
|
-     \( kvmalloc \| kvzalloc \)
+     vmemdup_user
)
                 (
-                 size, \( GFP_KERNEL \| GFP_USER \)
+                 from, size
                 );


Message:
25: no available token to attach to


Regards,
Markus