USB4BSD release candidate number 3 - request for review

[Hans Petter Selasky]

On Wednesday 05 November 2008, Rink Springer wrote:
> On Wed, Nov 05, 2008 at 02:18:17AM -0700, M. Warner Losh wrote:
> > In message: <200811050914.44225.hselasky at c2i.net>
> >
> >             Hans Petter Selasky <hselasky at c2i.net> writes:
> > : On Wednesday 05 November 2008, Lars Engels wrote:
> > : > Mounting a umass device, removing it and doing an 'ls' on the
> > : > mountpoint freezes the system, I thought this should not happen with
> > : > the new stack?
> > :
> > : It is not a USB problem. It is the CAM layer that is hanging on the
> > : disk.
> >
> > Sure it is CAM layer and not buffer cache or filesystem code?
>
> Well, the CAM layer problem will immediately first - it does not like
> CAM busses disappearing. Once this is fixed or avoided and the problem
> still shows up, we can blame buffer cache / filesystem code.
>
> As I suggested before, a good fix is to create one CAM bus per USB root
> hub, and use that to attach all umass devices to. This will also get rid
> of the one-bus-per-umass-device which is visually unappealling.
>

I've temporarily created one CAM bus per module, and release it when the 
usb2_storage_mass module is unloaded.

--HPS