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From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Jean Delvare <khali@linux-fr.org>
Subject: Re: [PATCH/RFC] pci: dynids.use_driver_data considered harmful
Date: Fri, 15 Aug 2008 12:15:01 -0700
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Cc: Greg KH <greg@kroah.com>, Milton Miller <miltonm@bga.com>,
       Michael Ellerman <michael@ellerman.id.au>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>, linux-pci@vger.kernel.org
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On Friday, August 15, 2008 11:55 am Jean Delvare wrote:
> In fact we can do even better than that. We could accept from
> user-space only driver_data values which at least one device ID entry in
> the driver already uses. That should be fairly easy to implement, and
> would offer a level of safety an order of magnitude above what we have
> at the moment... And it works both ways: if 0 is not a valid data for
> some driver, that would force the user to provide a non-zero (and
> valid) data value. And it guarantees that the user can't ask for
> something the driver doesn't expect, so drivers don't even need extra
> checks. And no need for a use_driver_data flag either.

Meaning a driver audit of the usage?  Yeah that would be great.

> The only drawback is that it prevents the user from passing a "new"
> data value even if it would be valid. But honestly, I don't expect that
> case to happen frequently... if ever at all. So I'd say the benefits
> totally outweight the drawback.
>
> If the interested people agree with the idea, I'll look into
> implementing it.

Well the audit would show if user supplied "new" values are needed; otherwise 
the approach sounds good to me.

Thanks
-- 
Jesse Barnes, Intel Open Source Technology Center
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