Re: libata timeouts when stressing a Samsung HDD

[Tejun Heo <tj@kernel.org>]

Hello,

Robert Hancock wrote:
>>> If I recall correctly, The reported shadow register contents are bogus
>>> when a timeout occurs.  So we don't actually know what the drive
>>> state was.
>>>
>>> Or do we, Tejun?
>>
>> Yeah, it's bogus.  Maybe we should just report zeros.
> 
> Didn't know that. Shouldn't we be able to do a qc_fill_rtf before error
> handling in this case? That would make it easier to tell if we lost an
> interrupt or if the drive is just taking too long..

I think Alan already did it in the patches which added improved
timeout handling callback.  Hmmm... Can't find it.  I thought it was
in #upstream.  Anyways, I'm slightly worried about reading status
blindly after timeout mainly due to experiences I had early while
developing libata EH.  Some controllers were simply scary and very
eager to lock up the whole machine.  That said, it could be that I'm
just overly paranoid.  After all, with shared IRQ, we don't have
control over when altstatus is read at least.

Thanks.

-- 
tejun