> And the transition after unplug goes
> 
> 13->12->10->8->7->6->5->3
> 
> implying we're missing put events.

Don't know why. I used this check (with trace_scsi_dev containing the name)
in put_device:

if (trace_scsi && dev->type == &scsi_dev_type &&
     trace_scsi_dev[0] == 0 || !strcmp(dev_name(dev), trace_scsi_dev))) {
	dev_printk ...

If you want instrumentation somewhere else please let me know.

Maybe there simply isn't a put_device to 0 and the NULL pointer happens
for some other reason?

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.