linux-kernel - Re: char/tpm: Improve a size determination in nine functions

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Date:   Tue, 17 Oct 2017 20:41:04 +0200
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        linux-integrity@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Cc:     Julia Lawall <julia.lawall@...6.fr>,
        Alexander Steffen <Alexander.Steffen@...ineon.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Corentin Labbe <clabbe.montjoie@...il.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Kenneth Goldman <kgold@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nayna Jain <nayna@...ux.vnet.ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Peter Hüwe <PeterHuewe@....de>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>
Subject: Re: char/tpm: Improve a size determination in nine functions

>> 	p = kmalloc(sizeof(*p), ...);
>>
>> The alternative form where struct name is spelled out hurts readability and
>> introduces an opportunity for a bug when the pointer variable type is changed
>> but the corresponding sizeof that is passed to a memory allocator is not.
> 
> True, thanks for the reminder.

Will it trigger further software development considerations (besides my contributions)?


> Is this common in new code?

Do you start an official survey here?


> Is there a script/ or some other automated way of catching this usage

Yes. - I am using an approach for the semantic patch language.   ;-)


> before patches are upstreamed?

I imagine that a corresponding source code analysis variant could be applied
in more cases if sufficient acceptance could be achieved.


> Just as you're doing here, the patch description should reference this
> in the patch description.

Do you find my wording “This issue was detected by using the Coccinelle software.” insufficient?

Regards,
Markus