Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
IronPort-SDR: dk4uSy5/5mV9glNjbiYCw1Acu1+N0Ii9Mpmhwl0tb+TUt59aYK2vxTK6JZ1NtAvNz1++7TTmSV
 hghmysMXc3EkE5th6e7W/eCpaX2sgbRe2FdtOy3wfId+ZxZAbYIevknXt5DJZkQ/Eyiqym6Zv0
 f9ofajfb1XVtOqVZXVOo4CC5CI9GlEEvyF1DRZOk+wFF9UcMmDceS3WHhCM5FuF8hJCfyeQN26
 rLFLXkJT1PCcqL4UZg/r9DHLay0jKBzzSroBv21O0Ut7PFFF2xLAFW9MNk3jiulpdWdA9mQU0i
 6jcXOA0yntikqNTQ8ybvkfcS
IronPort-SDR: dPdNJYUxB2R6kfLhQkEMKFTZ9PoyyIn9AEQQsbnINnw6ZxwLTGNvbvj49l1jUrVEQdsulctPPm
 uw+DPu6W7I9Tu7vAdZ0qKDvCr934P02kPtq/8MlnX6L2XsX8TJCEzpr6zLhqKCw9LETCzvSnqv
 o4vSbYLoycr41ZYUsiOFMHNSJ6+hYVgqTslQgSr8fslW74+wai/2HwBkGP0GbFwbmuyafui1VM
 dLWuun3zivPrBSc5cI4/QAzLXJrXsyIsP1ehvYDCADhSusCsl/99ObjkwmrwDveaRheIuiNlGr
 Y+Q=
WDCIronportException: Internal
Message-ID: <0c6c0c64-74f8-e15a-d79e-0866b5cc209d@opensource.wdc.com>
Date:   Wed, 6 Apr 2022 17:10:14 +0900
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.7.0
Subject: Re: [PATCH v2 1/2] libata: Use scsi cmnd budget token for qc tag for
 SAS host
Content-Language: en-US
To:     John Garry <john.garry@huawei.com>, hch@lst.de
Cc:     linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-scsi@vger.kernel.org
References: <1649083990-207133-1-git-send-email-john.garry@huawei.com>
 <1649083990-207133-2-git-send-email-john.garry@huawei.com>
 <a3cce73f-2e91-309d-bee0-a34a30335a18@opensource.wdc.com>
 <ab6a13c1-90c4-63f0-c48d-c1faa0ae68fd@huawei.com>
From:   Damien Le Moal <damien.lemoal@opensource.wdc.com>
Organization: Western Digital Research
In-Reply-To: <ab6a13c1-90c4-63f0-c48d-c1faa0ae68fd@huawei.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 4/6/22 16:12, John Garry wrote:
> On 06/04/2022 02:39, Damien Le Moal wrote:
>> On 4/4/22 23:53, John Garry wrote:
>>> For attaining a qc tag for a SAS host we need to allocate a bit in
>>> ata_port.sas_tag_allocated bitmap.
>>>
>>> However we already have a unique tag per device in range
>>> [0, ATA_MAX_QUEUE) in the scsi cmnd budget token, so just use that
>>> instead.
>>
>> The valid range is [0, ATA_MAX_QUEUE - 1]. Tag ATA_MAX_QUEUE is 
>> ATA_TAG_INTERNAL which is never allocated as a valid device tag but 
>> used directly in ata_exec_internal().
> 
> But that is what I have in [0, ATA_MAX_QUEUE), which is same as [0, 
> ATA_MAX_QUEUE - 1].

Oh ! I missed the ")" !
I would prefer an explicit [0, ATA_MAX_QUEUE - 1] to be clear :)

> 
> Thanks,
> john


-- 
Damien Le Moal
Western Digital Research