Re: [PATCH v2 2/2] uas: Make uas work with blk-mq

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Hi,

On 10/04/2014 04:46 PM, James Bottomley wrote:
> On Sat, 2014-10-04 at 10:53 +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 10/03/2014 11:47 PM, Greg Kroah-Hartman wrote:
>>> On Fri, Oct 03, 2014 at 12:08:57PM +0200, Hans de Goede wrote:
>>>> With uas over usb-3 the tags inside the uas iu-s must match the usb-3 stream
>>>> ids, and those go from 1 - qdepth.
>>>>
>>>> Before blk-mq calling scsi_activate_tcq(sdev, qdepth) guaranteed that we would
>>>> only get cmnd->request->tag from 0 - (qdepth - 1), and we used those as
>>>> uas-tags / stream-ids.
>>>>
>>>> With blk-mq however we are guaranteed to never get more then qdepth commands
>>>> queued at the same time, but the cmnd->request->tag values may be much larger,
>>>> which breaks uas.
>>>>
>>>> This commit fixes this by generating uas tags in the 1 - qdepth range ourselves
>>>> instead of using cmnd->request->tag.
>>>>
>>>> While touching all involved code anyways also rename the uas_cmd_info stream
>>>> field to uas_tag, because when using uas over usb-2 streams are not used.
>>>>
>>>> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
>>>> Reported-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
>>>> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
>>>> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
>>>
>>> This doesn't apply to my usb-next branch of usb.git, care to refresh it
>>> and resend?
>>
>> I did this v2 to resolve a conflict with a last minute fix for 3.17 which
>> James Bottomley pushed out yesterday. So if this does not apply that likely
>> is because that fix is not (yet) in next. See:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/jejb/scsi.git/log/?h=fixes
>>
>> And specifically:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/jejb/scsi.git/commit/?h=fixes&id=2c2d831c81ec75a7b0d8e28caa8e3d9c1fe546f9
>>
>> I'm not sure how to proceed here, maybe the best thing is to cherry pick
>> that fix into usb-next (should disappear on merge), and then apply
>> this one on top ?
> 
> Depends:  The fixes tree is based on -rc1, so you could just use that as
> the base for the topic branch uas goes in.  That's the usual way.  Or we
> could just do it via the SCSI tree, which will have the necessary base.
> 
> Which would you prefer?

This patch sits on top of a lot of other uas fixes which are already
in usb-next, so this needs to go in through usb-next.

Regards,

Hans
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