Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <ab6a13c1-90c4-63f0-c48d-c1faa0ae68fd@huawei.com>
Date:   Wed, 6 Apr 2022 08:12:08 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.6.1
Subject: Re: [PATCH v2 1/2] libata: Use scsi cmnd budget token for qc tag for
 SAS host
To:     Damien Le Moal <damien.lemoal@opensource.wdc.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>
From:   John Garry <john.garry@huawei.com>
In-Reply-To: <a3cce73f-2e91-309d-bee0-a34a30335a18@opensource.wdc.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

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].

Thanks,
john