On 02/01/2017 02:00 PM, Christoph Hellwig wrote:
> On Wed, Feb 01, 2017 at 12:26:39PM +0100, Hannes Reinecke wrote:
>> The low_dma value is always '1' in that branch, so the remaining
>> 'if' statement can never be reached.
>>
>>
>> Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
>> ---
>> drivers/scsi/sg.c | 9 ++-------
>> 1 file changed, 2 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
>> index dbe5b4b..652b934 100644
>> --- a/drivers/scsi/sg.c
>> +++ b/drivers/scsi/sg.c
>> @@ -890,14 +890,9 @@ static int max_sectors_bytes(struct request_queue *q)
>> result = get_user(val, ip);
>> if (result)
>> return result;
>> - if (val) {
>> + 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 {
>> + else {
>
> I think the proper fix is to check sfp->low_dma for 0 before updating
> it, at least that seems to be the intent here.
>
May. Or may not.
But this code path has _never_ been taken for the last ten years; this
particular code predates the initial git check-in from Linus.
Where would be the point of enabling it now?
(Especially given all the issues we're having with the sg driver ...)
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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HRB 21284 (AG Nürnberg)
