On 02/16/2017 11:23 AM, Sreekanth Reddy wrote:
> On Thu, Feb 16, 2017 at 3:44 PM, Hannes Reinecke <hare@xxxxxxx> wrote:
>> On 02/16/2017 11:09 AM, Sreekanth Reddy wrote:
>>> On Tue, Jan 31, 2017 at 2:55 PM, Hannes Reinecke <hare@xxxxxxx> wrote:
>>>> When sending a TMF via the ioctl interface we should be using
>>>> the hi-priority queue instead of the scsi queue to be consistent
>>>> with overall TMF usage.
>>>>
>>>> Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
>>>> ---
>>>> drivers/scsi/mpt3sas/mpt3sas_ctl.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
>>>> index 95f0f24..e952175 100644
>>>> --- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c
>>>> +++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
>>>> @@ -720,7 +720,7 @@ enum block_state {
>>>> }
>>>> } else {
>>>>
>>>> - smid = mpt3sas_base_get_smid_scsiio(ioc, ioc->ctl_cb_idx, NULL);
>>>> + smid = mpt3sas_base_get_smid_hpr(ioc, ioc->ctl_cb_idx);
>>>
>>> This else part is not for TM path, It is for IO path. For the TM
>>> request we are already using smid from hpr queue, as shown below
>>>
>>> if (mpi_request->Function == MPI2_FUNCTION_SCSI_TASK_MGMT) {
>>> smid = mpt3sas_base_get_smid_hpr(ioc, ioc->ctl_cb_idx);
>>> if (!smid) {
>>> pr_err(MPT3SAS_FMT "%s: failed obtaining a smid\n",
>>> ioc->name, __func__);
>>> ret = -EAGAIN;
>>> goto out;
>>> }
>>> } else {
>>>
>>> smid = mpt3sas_base_get_smid_scsiio(ioc, ioc->ctl_cb_idx, NULL);
>>>
>> Yes, I know.
>> But the current method of inserting a SCSI command completely goes
>> against blk-mq request usage; with blk-mq the tags are managed with the
>> block layer, so you need to integrate with that to get a correct tag.
>>
>> Is this _really_ a crucial functionality? Can't we just drop it and use
>> sg/bsg for this?
>> It would make my life _so_ much easier; the alternative would be to
>> either implement 'real' reserved command handling or rewriting the above
>> code-path in terms of 'struct request', packing and unpacking as we go.
>> Neither is very appealing.
>
> I think it is better to take out one request frame from can_queue
> count and reserve it for this ioctl scsi io. Since we allow only one
> ioctl command at a time.
>
Ok, that makes things easier. Will be updating the code.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
