linux-kernel - Re: [PATCH v3 4/9] scsi: ufs: Complete the cmd before returning in queuecommand

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Date:   Sat, 12 Jun 2021 15:38:14 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Bart Van Assche <bvanassche@....org>
Cc:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        hongwus@...eaurora.org, ziqichen@...eaurora.org,
        linux-scsi@...r.kernel.org, kernel-team@...roid.com,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 4/9] scsi: ufs: Complete the cmd before returning in
 queuecommand

On 2021-06-12 04:52, Bart Van Assche wrote:
> On 6/9/21 9:43 PM, Can Guo wrote:
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 0c9d2ee..7dc0fda 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -2758,6 +2758,16 @@ static int ufshcd_queuecommand(struct Scsi_Host 
>> *host, struct scsi_cmnd *cmd)
>>  		goto out;
>>  	}
>> 
>> +	if (unlikely(test_bit(tag, &hba->outstanding_reqs))) {
>> +		if (hba->wl_pm_op_in_progress) {
>> +			set_host_byte(cmd, DID_BAD_TARGET);
>> +			cmd->scsi_done(cmd);
>> +		} else {
>> +			err = SCSI_MLQUEUE_HOST_BUSY;
>> +		}
>> +		goto out;
>> +	}
>> +
>>  	hba->req_abort_count = 0;
>> 
>>  	err = ufshcd_hold(hba, true);
>> @@ -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,

Can Guo.

> Thanks,
> 
> Bart.