Tracking down ata0 reset hang

[Nate Lawson]

I have a laptop that suspends and resumes fine.  Soeren's patch to
properly reset the hardware after the ATAng import fixed the problem where
resuming would hang in ata0 reset with the hard drive light on.

Sometime in the last month or two, the ATA reset phase of resume has begun
hanging again with the drive light on and I can't break to the debugger.
The interesting data point is that if I suspend/resume in single user
mode, it works fine, including the reset.  But in multi-user mode, it
hangs.  I'm trying to disable various services to see if any of them
triggers the hang.

Has anyone else seen this regression?

-Nate