Re: [PATCH v4 1/2] scsi: ufs: Fix task management request completion timeout

[Bart Van Assche <bvanassche@acm.org>]

On 3/31/21 9:45 AM, Avri Altman 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@codeaurora.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 b49555fa..d4f8cb2 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -6464,6 +6464,7 @@ 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);
> Maybe just set req->state to MQ_RQ_IN_FLIGHT
> Without all other irrelevant initializations such as add timeout etc.

Hmm ... I'm not sure that any of the actions performed by
blk_mq_start_request() are irrelevant in this context. Additionally, no
other block or SCSI driver sets MQ_RQ_IN_FLIGHT directly.

Thanks,

Bart.