It's simple math, combined with user expectations.
On a 1-CPU or 2-CPU box, if you have three or more tasks, all of which
are doing hardware reset tasks that could take 30-60 seconds (realistic
for libata, SCSI and network drivers, at least), then OBVIOUSLY you have
other tasks blocked for that length of time.
Since the cause of the latency is msleep() -- the entire reason why the
driver wanted to use a kernel thread in the first place -- it would seem
to me that the simple fix is to start a new thread, possibly exceeding
the number of CPUs in the box.
That's been a problem in the past, yes, but a minor one.
I'm talking about a key conceptual problem with keventd.
It is easy to see how an extra-long tg3 hardware reset might prevent a
disk hotplug event from being processed for 30-60 seconds. And as
hardware gets more complex -- see the Intel IOP storage card which runs
Linux -- the reset times get longer, too.
So the issue is /not/ deadlocks.