linux-kernel - Re: [PATCH v3 1/3] scsi: ufs: Fix task management request completion timeout

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Message-ID: <1bcdd48c6afb079aadc8464847295363@codeaurora.org>
Date:   Fri, 29 Jan 2021 13:46:39 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Bart Van Assche <bvanassche@....org>
Cc:     jaegeuk@...nel.org, asutoshd@...eaurora.org,
        nguyenb@...eaurora.org, hongwus@...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>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/3] scsi: ufs: Fix task management request completion
 timeout

On 2021-01-29 11:22, Bart Van Assche wrote:
> On 1/27/21 8:16 PM, Can Guo wrote:
>> ufshcd_tmc_handler() calls blk_mq_tagset_busy_iter(fn = 
>> ufshcd_compl_tm()),
>> but since blk_mq_tagset_busy_iter() only iterates over all reserved 
>> tags
>> and requests which are not in IDLE state, ufshcd_compl_tm() never gets 
>> a
>> chance to run. Thus, TMR always ends up with completion timeout. Fix 
>> it by
>> calling blk_mq_start_request() in  __ufshcd_issue_tm_cmd().
>> 
>> Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to 
>> allocate and free TMFs")
>> 
>> Signed-off-by: Can Guo <cang@...eaurora.org>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 8da75e6..c0c5925 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -6395,6 +6395,7 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba 
>> *hba,
>> 
>>  	spin_lock_irqsave(host->host_lock, flags);
>>  	task_tag = hba->nutrs + free_slot;
>> +	blk_mq_start_request(req);
>> 
>>  	treq->req_header.dword_0 |= cpu_to_be32(task_tag);
> 
> blk_mq_start_request() not only marks a request as in-flight but also
> starts a timer. However, no timeout handler has been defined in
> ufshcd_tmf_ops. Should a timeout handler be defined in that data 
> structure?
> 

Block mq driver gives 30s as default timeout,
TMR timeout is 100ms in UFS driver. So we don't
need a timeout handler as of now.

Thanks,
Can Guo.

> Thanks,
> 
> Bart.