re: kern/46547: umass: sd crashes when synchronizing cache while trying to suspend

[matthew green <mrg%eterna.com.au@localhost>]

this smells like what i did to amd64 cpu_reboot() to make it not crash
when rebooting when usb disks are present.  this ended up trying to 
perform a sync. operation from a softint handler, which triggers
checks in cv_wait() or tsleep

note that i didn't say "fix".  :-(  i'm not really sure what the right
solution here is.  can you try a kernel with LOCKDEBUG enabled and
show us the full output?

i did try having these events run from the USB task thread but that
just left me with a soft-hung system at reboot.  it was about then
that i noticed i386 and amd64 cpu_reboot() were pretty different and
when i made amd64 like i386, i had no more crashes.  however, that
really only happens because cpu_reboot() arranges it, not that the
problem was actually fixed.


.mrg.