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Subject: Re: [PATCH v3 4/9] scsi: ufs: Complete the cmd before returning in
 queuecommand
To:     Can Guo <cang@codeaurora.org>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        hongwus@codeaurora.org, ziqichen@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        open list <linux-kernel@vger.kernel.org>
References: <1623300218-9454-1-git-send-email-cang@codeaurora.org>
 <1623300218-9454-5-git-send-email-cang@codeaurora.org>
 <d017548a-16fb-8ad0-2363-09dad00c9642@acm.org>
 <80926df7e3e41088e59ce5e0dbdec28a@codeaurora.org>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <5df201d5-ab7f-a9fc-36aa-6dd174e9cee2@acm.org>
Date:   Sat, 12 Jun 2021 08:50:12 -0700
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On 6/12/21 12:38 AM, Can Guo wrote:
> On 2021-06-12 04:52, Bart Van Assche wrote:
>> On 6/9/21 9:43 PM, Can Guo wrote:
>>> @@ -2768,15 +2778,6 @@ static int ufshcd_queuecommand(struct
>>> Scsi_Host *host, struct scsi_cmnd *cmd)
>>>      WARN_ON(ufshcd_is_clkgating_allowed(hba) &&
>>>          (hba->clk_gating.state != CLKS_ON));
>>>
>>> -    if (unlikely(test_bit(tag, &hba->outstanding_reqs))) {
>>> -        if (hba->wl_pm_op_in_progress)
>>> -            set_host_byte(cmd, DID_BAD_TARGET);
>>> -        else
>>> -            err = SCSI_MLQUEUE_HOST_BUSY;
>>> -        ufshcd_release(hba);
>>> -        goto out;
>>> -    }
>>> -
>>>      lrbp = &hba->lrb[tag];
>>>      WARN_ON(lrbp->cmd);
>>>      lrbp->cmd = cmd;
>>
>> Can the code under "if (unlikely(test_bit(tag,
>> &hba->outstanding_reqs)))" be deleted instead of moving it? I don't
>> think that it is useful to verify whether the block layer tag allocator
>> works correctly. Additionally, I'm not aware of any similar code in any
>> other SCSI LLD.
> 
> ufshcd_abort() aborts PM requests differently from other requests -
> it simply evicts the cmd from lrbp [1], schedules error handler and
> returns SUCCESS (the reason why I am doing it this way is in patch #8).
> 
> After ufshcd_abort() returns, the tag shall be released, the logic
> here is to prevent subsequent cmds re-use the lrbp [1] before error
> handler recovers the device and host.

Thanks for the background information. However, this approach sounds
cumbersome to me. For PM requests, please change the UFS driver such
that calling scsi_done() for aborted requests is postponed until error
handling has finished and delete the code shown above from
ufshcd_queuecommand().

Thanks,

Bart.