some changes to xpt to help make unloading sim modules safer

[Matthew Jacob]

On 8/8/2011 7:52 AM, Chuck Tuffli wrote:
> On Sun, Aug 7, 2011 at 2:27 PM, Matthew Jacob<mj at feral.com>  wrote:
>> See http://people.freebsd.org/~mjacob/xpt_patches.txt
> Matt -
>
> Thanks for doing this. So it seems the rule is to hold
> xsoftc.xpt_topo_lock while modifying bus->refcount . If so, does
> xpt_alloc_target need mtx_lock() / mtx_unlock() around bus->refcount++
> ?
>
>

By jove, I think you're right!