linux-kernel - Re: [PATCH v2 2/5] ufs: mcq: Add support for clean up mcq resources

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Message-ID: <b1af6459-43b7-d193-c6e7-37f24d7349e6@quicinc.com>
Date:   Wed, 3 May 2023 21:01:25 -0700
From:   "Bao D. Nguyen" <quic_nguyenb@...cinc.com>
To:     Bart Van Assche <bvanassche@....org>, <quic_asutoshd@...cinc.com>,
        <quic_cang@...cinc.com>, <mani@...nel.org>,
        <Powen.Kao@...iatek.com>, <stanley.chu@...iatek.com>,
        <adrian.hunter@...el.com>, <beanhuo@...ron.com>,
        <avri.altman@....com>, <martin.petersen@...cle.com>
CC:     <linux-scsi@...r.kernel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/5] ufs: mcq: Add support for clean up mcq resources

On 4/25/2023 5:08 PM, Bart Van Assche wrote:
> On 4/17/23 14:05, Bao D. Nguyen wrote:
>> @@ -3110,7 +3128,7 @@ static int ufshcd_wait_for_dev_cmd(struct 
>> ufs_hba *hba,
>>           err = -ETIMEDOUT;
>>           dev_dbg(hba->dev, "%s: dev_cmd request timedout, tag %d\n",
>>               __func__, lrbp->task_tag);
>> -        if (ufshcd_clear_cmds(hba, 1U << lrbp->task_tag) == 0) {
>> +        if (ufshcd_clear_cmds(hba, 1UL << lrbp->task_tag) == 0) {
>>               /* successfully cleared the command, retry if needed */
>>               err = -EAGAIN;
>>               /*
> 
> Is this change necessary?
My intention was to support tag greater than 31 and less than 64.
The 1U << only works up to 32 bits.

> 
>> @@ -7379,6 +7397,20 @@ static int ufshcd_try_to_abort_task(struct 
>> ufs_hba *hba, int tag)
>>                */
>>               dev_err(hba->dev, "%s: cmd at tag %d not pending in the 
>> device.\n",
>>                   __func__, tag);
>> +            if (is_mcq_enabled(hba)) {
>> +                /* MCQ mode */
>> +                if (lrbp->cmd) {
>> +                    /* sleep for max. 200us to stabilize */
> 
> What is being stabilized here? Please make this comment more clear.
This is to keep the same operation/timing as in SDB mode.

> 
>> +                    usleep_range(100, 200);
>> +                    continue;
>> +                }
>> +                /* command completed already */
>> +                dev_err(hba->dev, "%s: cmd at tag=%d is cleared.\n",
>> +                    __func__, tag);
>> +                goto out;
>> +            }
> 
> Please do not use lrbp->cmd to check whether or not a command has 
> completed. See also my patch "scsi: ufs: Fix handling of lrbp->cmd".
I have been thinking how to replace lrbp->cmd, but could not find a good 
solution. Throughout this patch series, I am using lrbp->cmd as a way to 
find the pending command that is being aborted and clean up the 
resources associated with it. Any suggestions to achieve it? Thanks.

> 
>> @@ -7415,7 +7447,7 @@ static int ufshcd_try_to_abort_task(struct 
>> ufs_hba *hba, int tag)
>>           goto out;
>>       }
>> -    err = ufshcd_clear_cmds(hba, 1U << tag);
>> +    err = ufshcd_clear_cmds(hba, 1UL << tag);
>>       if (err)
>>           dev_err(hba->dev, "%s: Failed clearing cmd at tag %d, err 
>> %d\n",
>>               __func__, tag, err);
> 
> Is this change necessary?
Same as above, I intended  to support 64 > tag > 31

> 
>> -    if (!(test_bit(tag, &hba->outstanding_reqs))) {
>> +    if (!is_mcq_enabled(hba) && !(test_bit(tag, 
>> &hba->outstanding_reqs))) {
> 
> Please leave out one pair of superfluous parentheses from the above 
> expression.
Yes, I will change.

> 
> Thanks,
> 
> Bart.