On 02/17/2017 01:38 PM, Christoph Hellwig wrote:
> On Fri, Feb 17, 2017 at 09:23:10AM +0100, Hannes Reinecke wrote:
>> The mpt3sas driver requires a reserved command space to handle
>> SCSI passthrough commands.
>>
>> Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
>> ---
>> drivers/scsi/mpt3sas/mpt3sas_base.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
>> index e9470a3..97189ad 100644
>> --- a/drivers/scsi/mpt3sas/mpt3sas_base.c
>> +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
>> @@ -2360,6 +2360,8 @@ struct scsiio_tracker *
>> } else {
>> u32 unique_tag = blk_mq_unique_tag(scmd->request);
>> u16 tag = blk_mq_unique_tag_to_tag(unique_tag);
>> +
>> + WARN_ON(tag < ioc->shost->reserved_cmds);
>> request = scsi_cmd_priv(scmd);
>> smid = tag + 1;
>> }
>> @@ -3521,7 +3523,8 @@ void mpt3sas_base_clear_st(struct MPT3SAS_ADAPTER *ioc,
>> /* set the scsi host can_queue depth
>> * with some internal commands that could be outstanding
>> */
>> - ioc->shost->can_queue = ioc->scsiio_depth - INTERNAL_SCSIIO_CMDS_COUNT;
>> + ioc->shost->reserved_cmds = INTERNAL_SCSIIO_CMDS_COUNT;
>> + ioc->shost->can_queue = ioc->scsiio_depth - ioc->shost->reserved_cmds;
>
> You're never allocating a reserved request. Just remove the number of
> reserved cmds from can_queue and you can use them on your own.
>
> So I don't think you'll actually need to use reserved request here,
> but instead you should set up can_queue properly earlier in the series.
>
Well, once I'm switching over to embedded commands I'll have to
integrate with SCSI midlayer to actually _allocate_ the tracker
structure for me.
At the same time the midlayer should _not_ use that structure for normal
I/O; which sounds suspiciously like reserved commands to me ...
Oh well; guess I'll have to do it, then.
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
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