Re: [PATCH] scsi: libsas: Directly kick-off EH when ATA device fell off

[yangxingui <yangxingui@huawei.com>]

On 2022/12/16 11:53, Jason Yan wrote:
> Hi Xingui,
> 
> On 2022/12/16 11:29, Xingui Yang wrote:
>> If the ATA device fell off, call sas_ata_device_link_abort() directly and
>> mark all outstanding QCs as failed and kick-off EH Immediately. This 
>> avoids
>> having to wait for block layer timeouts.
>>
> 
> Why does ATA device need this special operation? SAS device does not 
> have to wait for block layer timeouts?
Hi Jason,
Applications that depend on I/O return may be blocked for 30 seconds, 
and this can be optimized for SATA disks.

Different from SATA disks, I/Os on SAS disks can still be returned if 
they are quickly plugged in after the SAS disks fall off. So I'm not 
sure if this is appropriate for a sas disk.
BTW, I wish the sas disk did the same.

Thanks,
Xingui
> 
> Thanks,
> Jason
> 
>> Signed-off-by: Xingui Yang <yangxingui@huawei.com>
>> ---
>>   drivers/scsi/libsas/sas_discover.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/scsi/libsas/sas_discover.c 
>> b/drivers/scsi/libsas/sas_discover.c
>> index d5bc1314c341..bd22741daa99 100644
>> --- a/drivers/scsi/libsas/sas_discover.c
>> +++ b/drivers/scsi/libsas/sas_discover.c
>> @@ -362,6 +362,11 @@ static void sas_destruct_ports(struct 
>> asd_sas_port *port)
>>   void sas_unregister_dev(struct asd_sas_port *port, struct 
>> domain_device *dev)
>>   {
>> +    if (test_bit(SAS_DEV_GONE, &dev->state) &&
>> +        (dev->dev_type == SAS_SATA_DEV ||
>> +        (dev->tproto & SAS_PROTOCOL_STP)))
>> +        sas_ata_device_link_abort(dev, false);
>> +
>>       if (!test_bit(SAS_DEV_DESTROY, &dev->state) &&
>>           !list_empty(&dev->disco_list_node)) {
>>           /* this rphy never saw sas_rphy_add */
>>
> .