On 02/03/2017 10:32 AM, Johannes Thumshirn wrote:
>
> On 02/03/2017 09:54 AM, Hannes Reinecke wrote:
>> The ioctl SET_FORCE_LOW_DMA has never worked since the initial
>> git check-in, and the respective setting is nowadays handled
>> correctly.
>> So disable it entirely.
>>
>> Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
>> ---
>
> [...]
>
>> case SG_SET_FORCE_LOW_DMA:
>> - result = get_user(val, ip);
>> - if (result)
>> - return result;
>> - if (val) {
>> - sfp->low_dma = 1;
>> - if ((0 == sfp->low_dma) && (0 == sg_res_in_use(sfp))) {
>> - val = (int) sfp->reserve.bufflen;
>> - sg_remove_scat(sfp, &sfp->reserve);
>> - sg_build_reserve(sfp, val);
>> - }
>> - } else {
>> - if (atomic_read(&sdp->detaching))
>> - return -ENODEV;
>> - sfp->low_dma = sdp->device->host->unchecked_isa_dma;
>> - }
>> - return 0;
>> + return -EINVAL;
>
> I'm not sure if returning a bogus '0' is better here to not break any
> existing application, which assumed it always worked.
>
Well, the ioctl already was returning error numbers, so any calling
application had to protect against that.
And I don't really see the point to protect against failures in legacy
applications relying on a functionality which never did anything.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
