Re: [PATCH 1/2] scsi: core: Add support for reserved tags

[Hannes Reinecke <hare@suse.de>]

On 11/10/21 8:19 PM, Bart Van Assche wrote:
> On 11/9/21 10:59 PM, Hannes Reinecke wrote:
>> This is essentially the same patch as I posted a while ago (cf 
>> https://lore.kernel.org/linux-scsi/20210222132405.91369-1- 
>> hare@suse.de/).
>>
>> But there had been push-back on that series as it would also try to 
>> use a scsi host device for driver-internal commands.
>>
>> Maybe we should combine our efforts; patch 2 is equivalent to your 
>> patch, and 3-5 are a conversion of the fnic driver to use those 
>> commands. So we should merge our efforts to get this thing off the 
>> ground.
>>
>> For the remainder of the patchset I'm currently working on a solution 
>> to address the upstream concerns.
> 
> Hi Hannes,
> 
> In the UFS driver we are using a request queue that is not associated 
> with any SCSI device for allocating driver-internal tags from the same 
> tags space as SCSI commands. Is this a solution that is generic enough 
> to be re-used by other SCSI drivers? See also the output of git grep -nH 
> 'hba->cmd_queue'.
> 
Ah. Even easier.
I've made a prototype for this kind of operation in
git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git
branch scsi-internal.v1

That introduces a function 'scsi_host_get_internal_tag()'
to retrieve a tag from the reserved pool of the host tagset.
Would that work for you?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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