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

> , 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. 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...


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