linux-kernel - Re: [PATCH] coccinelle: api: add kvfree script

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Date:   Sat, 6 Jun 2020 09:30:36 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Denis Efremov <efremov@...ux.com>,
        Coccinelle <cocci@...teme.lip6.fr>,
        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>
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] coccinelle: api: add kvfree script

> Check that alloc and free types of functions match each other.

Further software development challenges are interesting also for such an use case.

> +/// Check that kvmalloc'ed memory is freed by kfree functions,
> +/// vmalloc'ed by vfree functions and kvmalloc'ed by kvfree
> +/// functions.

* How do you think about to offer a wording suggestion for subjects of
  generated patches?

* Will the presented case distinction trigger further improvements for
  the desired matching?

* Would you like to generalise the safe handling of allocations
  and corresponding release of system resources?

> +// Confidence: High

I suggest to reconsider this information once more.

> +virtual patch
> +virtual report
> +virtual org
> +virtual context

+virtual patch, report, org, context

Is such a SmPL code variant more succinct?

> +@...ice@

* Can it be that this SmPL rule is not relevant for all operation modes?

* Will additional dependencies matter?

> +    E = \(kmalloc@kok\|kzalloc@kok\|krealloc@kok\|kcalloc@kok\|kmalloc_node@kok\|kzalloc_node@kok\|kmalloc_array@kok\|kmalloc_array_node@kok\|kcalloc_node@kok\)(...)

I would prefer an other coding style here.

* Items for such SmPL disjunctions can be specified also on multiple lines.

* The semantic patch language supports further means to handle function name lists
  in more convenient ways.
  Would you like to work with customised constraints?

> +msg = "WARNING: kmalloc is used to allocate this memory at line %s" % (k[0].line)
> +coccilib.report.print_report(p[0], msg)

* I propose once more omit the extra variable “msg” at similar places.
  The desired message object can be directly passed as a function parameter.

* I find the diagnostic text insufficient.

* Can the corresponding function category be dynamically determined?

Are you looking for opportunities to avoid unwanted code duplication?

Regards,
Markus