Messages in this thread | | | From | Milton Miller <> | Subject | Re: [PATCH/RFC] pci: dynids.use_driver_data considered harmful | Date | Tue, 19 Aug 2008 13:01:47 -0500 |
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On Aug 17, 2008, at 2:06 PM, Jean Delvare wrote: > On Fri, 15 Aug 2008 23:22:59 -0700, Greg KH wrote: >> On Fri, Aug 15, 2008 at 12:15:01PM -0700, Jesse Barnes wrote: >>> 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.
Thanks Jean for doing this. Sometimes things move quickly after a long stall. I thought about proposing a similar patch and therefore have to say Ack.
>>>> 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.
There are a few drivers that could benefit, mainly ones that I identified as using flags. For example, the radeon driver uses different fields of the data to specify crt controller, video output device, etc. I'm fine with deferring a flag for such drivers until someone audits a driver and wants the support.
>>>> >>>> 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. >> >> That sounds reasonable, and should work properly. >> >> No objection from me.
so, if anyone asks,
Concept-Acked-By: Milton Miller <miltonm@bga.com>
milton
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