Date:   Fri, 28 Apr 2023 16:01:45 +0800
From:   yangxingui <yangxingui@...wei.com>
To:     Jason Yan <yanaijie@...wei.com>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>, <john.g.garry@...cle.com>
CC:     <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <prime.zeng@...ilicon.com>,
        <kangfenglong@...wei.com>
Subject: Re: [PATCH] scsi: libsas: set tf to normal in
 sas_ata_device_link_abort()



On 2023/4/26 9:41, Jason Yan wrote:
> On 2023/4/17 16:18, yangxingui wrote:
>> Hi Jason
>>
>> On 2023/4/14 15:36, Jason Yan wrote:
>>> On 2023/4/7 11:56, Xingui Yang wrote:
>>>> If the disk returns UNC for more than five times within a short 
>>>> period, the
>>>> number of retry times for other I/Os may reach scmd->allowed, and the
>>>> default error "Illegal Request" is returned for other I/Os, as follows:
>>>>
>>>> [  273.801770] hisi_sas_v3_hw 0000:b4:02.0: erroneous completion 
>>>> disk err dev id=2 sas_addr=0x5000000000000605 CQ hdr: 0x400903 
>>>> 0x20103 0x0 0x80470000
>>>> [  273.875286] sas: Enter sas_scsi_recover_host busy: 30 failed: 30
>>>> [  273.879895] sas: trying to find task 0x00000000d9cfc893
>>>> [  273.879896] sas: sas_scsi_find_task: aborting task 
>>>> 0x00000000d9cfc893
>>>> [  273.880054] sas: sas_scsi_find_task: task 0x00000000d9cfc893 is done
>>>> [  273.880055] sas: sas_eh_handle_sas_errors: task 
>>>> 0x00000000d9cfc893 is done
>>>> [  273.880236] ata6.00: failed command: READ FPDMA QUEUED
>>>> [  273.880238] ata6.00: cmd 60/08:00:59:27:00/00:00:00:00:00/40 tag 
>>>> 22 ncq dma 4096 in
>>>>                          res 41/04:00:20:00:00/00:00:00:00:00/00 
>>>> Emask 0x1 (device error)
>>>> [  273.880239] ata6.00: status: { DRDY ERR }
>>>> [  273.880240] ata6.00: error: { ABRT }
>>>> [  273.880241] ata6.00: failed command: READ FPDMA QUEUED
>>>> [  273.880243] ata6.00: cmd 60/90:00:d1:26:00/00:00:00:00:00/40 tag 
>>>> 23 ncq dma 73728 in
>>>>                          res 41/40:90:10:27:00/00:00:00:00:00/00 
>>>> Emask 0x409 (media error) <F>
>>>> [  273.880245] ata6.00: status: { DRDY ERR }
>>>> [  273.880246] ata6.00: error: { UNC }
>>>> [  273.880247] ata6.00: failed command: READ FPDMA QUEUED
>>>> [  273.880249] ata6.00: cmd 60/08:00:19:27:00/00:00:00:00:00/40 tag 
>>>> 24 ncq dma 4096 in
>>>>                          res 41/04:00:20:00:00/00:00:00:00:00/00 
>>>> Emask 0x1 (device error)
>>>> [  273.880250] ata6.00: status: { DRDY ERR }
>>>> [  273.880251] ata6.00: error: { ABRT }
>>>> [  274.199477] scmd->retries: 3, scmd->allowed: 5
>>>> [  274.199478] scmd->retries: 3, scmd->allowed: 5
>>>> [  274.199479] scmd->retries: 3, scmd->allowed: 5
>>>> [  274.199481] scmd->retries: 3, scmd->allowed: 5
>>>> [  274.199482] scmd->retries: 3, scmd->allowed: 5
>>>> [  274.199483] scmd->retries: 2, scmd->allowed: 5
>>>> [  274.199484] scmd->retries: 3, scmd->allowed: 5
>>>> [  274.199485] scmd->retries: 3, scmd->allowed: 5
>>>> [  274.199486] scmd->retries: 5, scmd->allowed: 5
>>>> [  274.199487] scmd->retries: 2, scmd->allowed: 5
>>>> [  274.199488] scmd->retries: 2, scmd->allowed: 5
>>>> [  274.199524] sd 6:0:1:0: [sdb] tag#258 FAILED Result: 
>>>> hostbyte=DID_OK driverbyte=DRIVER_SENSE
>>>> [  274.199527] sd 6:0:1:0: [sdb] tag#258 Sense Key : Illegal Request 
>>>> [current]
>>>> [  274.199530] sd 6:0:1:0: [sdb] tag#258 Add. Sense: Unaligned write 
>>>> command
>>>> [  274.199532] sd 6:0:1:0: [sdb] tag#258 CDB: Read(10) 28 00 00 00 
>>>> 27 59 00 00 08 00
>>>> [  274.199535] print_req_error: I/O error, dev sdb, sector 10073
>>>> [  274.199573] sd 6:0:1:0: [sdb] tag#259 FAILED Result: 
>>>> hostbyte=DID_OK driverbyte=DRIVER_SENSE
>>>> [  274.199574] sd 6:0:1:0: [sdb] tag#259 Sense Key : Medium Error 
>>>> [current]
>>>> [  274.199576] sd 6:0:1:0: [sdb] tag#259 Add. Sense: Unrecovered 
>>>> read error - auto reallocate failed
>>>> [  274.199578] sd 6:0:1:0: [sdb] tag#259 CDB: Read(10) 28 00 00 00 
>>>> 26 d1 00 00 90 00
>>>> [  274.199579] print_req_error: I/O error, dev sdb, sector 10000
>>>> [  274.199608] ata6: EH complete
>>>> [  274.199615] sas: --- Exit sas_scsi_recover_host: busy: 0 failed: 
>>>> 30 tries: 1
>>>>
>>>> As mentioned in ata_eh_qc_retry(), if qc->err_mask is zero then 
>>>> increment
>>>> scmd->allowed. So set tf to normal may be better.
>>>
>>> Hi Xingui,
>>>
>>> If we increase scmd->allowed every time, and the device returns UNC 
>>> for too many times, will the other IO pending for too long and cause 
>>> hungtask? And also the runtime check in scsi_cmd_runtime_exceeced() 
>>> will not trigger since cmd->allowed is extended.
>>>
>> Thank you for your reply. In scenarios similar to UNC error, where a 
>> disk returns an error through D2H or SDB, no error is reported for 
>> other I/Os in the disk. In this case, AHCI will increase the number of 
>> retry times for other I/Os, and AHCI may face similar problems you 
>> say, but default failures may not be very good for users.
> 
Hi Jason
> I think at least we cannot always retry unconditionally. Failure is 
> better than hung becuase users can deal with failures. They can retry 
> from the userspace. But if the process stuck in kernel, it is a disaster 
> for the userspace and they can do nothing. Is there a way to limit the 
> times of retry
During this period, the user will receive the I/O error of UNC all the 
time unless the user stops accessing the disk.

Thanks,
Xingui
> 
> Thanks,
> Jason
> 
>>
>> In addition, for commands with pass through type, other I/Os are 
>> immediately returned with default errors and are not retried, but AHCI 
>> only report one single error I/O.
>>
>> Thanks,
>> Xingui
>>
>>> Thanks,
>>> Jason
>>>
>>>>
>>>> Signed-off-by: Xingui Yang <yangxingui@...wei.com>
>>>> ---
>>>>   drivers/scsi/libsas/sas_ata.c | 4 ++--
>>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/scsi/libsas/sas_ata.c 
>>>> b/drivers/scsi/libsas/sas_ata.c
>>>> index 77714a495cbb..f5047e8dcb59 100644
>>>> --- a/drivers/scsi/libsas/sas_ata.c
>>>> +++ b/drivers/scsi/libsas/sas_ata.c
>>>> @@ -949,8 +949,8 @@ void sas_ata_device_link_abort(struct 
>>>> domain_device *device, bool force_reset)
>>>>       unsigned long flags;
>>>>       spin_lock_irqsave(ap->lock, flags);
>>>> -    device->sata_dev.fis[2] = ATA_ERR | ATA_DRDY; /* tf status */
>>>> -    device->sata_dev.fis[3] = ATA_ABORTED; /* tf error */
>>>> +    device->sata_dev.fis[2] = ATA_DRDY; /* tf status */
>>>> +    device->sata_dev.fis[3] = 0;        /* tf error */
>>>>       link->eh_info.err_mask |= AC_ERR_DEV;
>>>>       if (force_reset)
>>>>
>>> .
>> .
> .

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