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SubjectRe: [PATCH V2] scsi: libsas: Directly kick-off EH when ATA device fell off

On 2022/12/19 22:53, John Garry wrote:
> On 19/12/2022 12:59, yangxingui wrote:
>>> Firstly, I think that there is a bug in sas_ata_device_link_abort()
>>> -> ata_link_abort() code in that the host lock in not grabbed, as the
>>> comment in ata_port_abort() mentions. Having said that, libsas had
>>> already some dodgy host locking usage - specifically dropping the
>>> lock for the queuing path (that's something else to be fixed up ... I
>>> think that is due to queue command CB calling task_done() in some
>>> cases), but I still think that sas_ata_device_link_abort() should be
>>> fixed (to grab the host lock).
>> ok, I agree with you very much for this, I had doubts about whether we
>> needed to grab lock before.
> ok, I hope that you can fix this up separately.
>>> Secondly, this just seems like a half solution to the age-old problem
>>> - that is, EH eventually kicking in only after 30 seconds when a disk
>>> is removed with active IO. I say half solution as SAS disks still
>>> have this issue for libsas. Can we instead push to try to solve both
>>> of them now?
>> Jason said you must have such an opinion "a half solution". As libsas
>> does not have any interface to mark all outstanding commands as failed
>> for SAS disk currently and SAS disk support I/O resumable transmission
>> after intermittent disconnections
> I don't know what you mean by "resumable transmission after intermittent
> disconnections".
>> , so I want to optimize sata disk first.
>> If we want to achieve a complete solution, perhaps we need to define
>> such an interface in libsas and implement it by lldd. My current idea
>> is to call sas_abort_task() for all outstanding commands in lldd. I
>> wonder if you approve of this?
> Are you sure you mean sas_abort_task()? That is for the LLDD to issue an
> abort TMF. I assume that you mean sas_task_abort(). If so, I am not too
> keen on the idea of libsas calling into the LLDD to inform of such an
> event.
I've implemented this solution. The verification seems to be ok both for
sas/sata device. I'll update the version again. Please have a look?

Note that maybe a tagset iter function could be used by libsas to
> abort each active IO, but I don't like libsas messing with such a thing;
> in addition, there may be some conflict between libsas aborting the IO
> and the IO completing with error in the LLDD.
> Please note that I need to refresh my memory on this whole EH topic...
> Thanks,
> John
> .

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