Re: PATCH libata-2.6 4/5] Prevent the device from overrunning the buffer in __atapi_pio_bytes()

[Jeff Garzik <jgarzik@pobox.com>]

Albert Lee wrote:
>  >
>  > Bartlomiej Zolnierkiewicz wrote:
> 
>>>
>>> Problem:
>>>   Some bad behaved CD-ROM drives will return more data than ask to.
>>> (I have such CD-RW drive and it crashed the kernel.)
>>
>>
>>
>> These devices are compliant with original ATAPI spec.
>>
>> Such condition shouldn't be treated as an error
>> - extra data should be read and dumped.
>>
>>
> Hi Bart,
> 
> For read, we can read and discard the extra data from the device.
> For write, the device is asking for more data than we have.
> Should we supply some dummy data to the device? Or we just stop and 
> return it as error?

For write, we need to pad.  For DMA, we need to add additional zeroes, 
until the DMA transfer ends on a dword boundary.  For PIO, we must at 
least pad to a word boundary.

	Jeff