Re: [REGRESSION 3.17] scsi (uas) disks no longer using tagged command queuing

From: Hans de Goede
Date: Thu Sep 11 2014 - 06:01:45 EST


Hi,

On 09/10/2014 05:45 PM, Christoph Hellwig wrote:
> On Wed, Sep 10, 2014 at 09:21:24AM +0200, Hans de Goede wrote:
>> I've applied the patch, this results in the following new dmesg output
>> when using uas:
>>
>> [ 120.602632] initialized host-wide tag map!
>>
>> Thank you for looking into this.
>
> So we're initializing the tag map, but scsi_activate_tcq doesn't pick it
> up. I can't really come up with a good explanation for it, but there
> even without that there is an elephant in the room: as part of the
> scsi-mq series I moved the bqt field used for this into a union with the
> new blk_mq_tag_set. Below is a patch to get rid of that union, can you
> try if that fixes it?

Unfortunately that does not fix it :|

Regards,

Hans

>
>
> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
> index d0f69a3..bcffff2 100644
> --- a/include/scsi/scsi_host.h
> +++ b/include/scsi/scsi_host.h
> @@ -584,10 +584,8 @@ struct Scsi_Host {
> * Area to keep a shared tag map (if needed, will be
> * NULL if not).
> */
> - union {
> - struct blk_queue_tag *bqt;
> - struct blk_mq_tag_set tag_set;
> - };
> + struct blk_queue_tag *bqt;
> + struct blk_mq_tag_set tag_set;
>
> atomic_t host_busy; /* commands actually active on low-level */
> atomic_t host_blocked;
>
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