Re: [PATCH #upstream 2/2] libata: track SLEEP state and issue SRST to wake it up

[Tejun Heo <htejun@gmail.com>]

Andrew Paprocki wrote:
> Tejun,
> 
> I'm able to break my system using this patch. I had a hunch this might
> be possible.. :) In short, if you issue a sleep command while the
> drive is already sleeping, it puts libata into an infinite loop
> resetting the port. I've illustrated the working test and the evil
> hunch below. The sleep command itself will need a short-circuit out of
> this logic in order to prevent this loop.

Heh... I guess you're much better a software engineer than I am.  Thanks
for finding it out.  It was stupid of me.  :-)

> Also, in the working case below the hddtemp command actually blocked
> until the drive was spun up before returning a valid temp. While
> testing, I was able to get hddtemp to trigger the drive wake-up when
> it was sleeping, but hddtemp then returned stating the drive was
> sleeping. Re-running hddtemp until the drive was fully spun up
> (another 5 seconds) kept returning that it was sleeping. I'll see if I
> can reproduce this reliably. Am I correct in assuming the process
> which triggers the wake-up should block?

Yeah, it should.  I'll test with hddtemp myself.

Jeff, please forget about this patchset.  I'll re-post updated version.

-- 
tejun