NEWBUS states (was Re: svn commit: r196779 - in head/sys: kern sys)

[John Baldwin]

On Saturday 12 September 2009 4:09:21 am Hans Petter Selasky wrote:
> On Tuesday 08 September 2009 15:36:37 John Baldwin wrote:
> > On Friday 04 September 2009 6:46:03 pm Attilio Rao wrote:
> > > We all agreed the one-state was the better option but it can't be done
> > > in this way because of the device_is_attached() used in the detach
> > > virtual functions. Using just one transition state will break
> > > device_is_attached() in those parts.
> > > The right fix, as pointed out in other e-mails, is to not use
> > > device_is_attached() in detach virtual functions. The better fix, in
> > > my idea would involve:
> > > - replace the device_is_attached() usage in detach virtual functions,
> > > with a more functional support
> > > - use one-state transition
> > >
> > > But that is just too much job to push in before then 8.0-REL and if
> > > that would mean to not commit a patch and make impossible a future
> > > MFC, I prefer to go with a lesser-perfect-but-still-working-approach.
> >
> > Wait, all you need to MFC is the change to the enum.  Fixing the various
> > detach routines does _not_ have to be in 8.0.  That could be merged after
> > the release.
> 
> Hi,
> 
> 
http://svn.freebsd.org/viewvc/base/head/sys/kern/subr_bus.c?r1=196529&r2=196779
> 
> I'm sorry to say that the latest patches to subr_bus.c have broken USB. I've 
> got several reports on memory used after free, due to bus_generic_detach() 
> returning EBUSY when called from uhub_detach().
> 
> ...
> bus_generic_detach(device_t dev)
> {
>         device_t child;
>         int error;
> 
>         if (dev->state != DS_ATTACHED)
>                 return (EBUSY);
> 
>         TAILQ_FOREACH(child, &dev->children, link) {
>                 if ((error = device_detach(child)) != 0)
>                         return (error);
>         }
> 
>         return (0);
> }
> 
> A fix for USB is available here:
> 
> http://perforce.freebsd.org/chv.cgi?CH=168387

I think bus_generic_detach() needs to work when called from a foo_detach() 
routine, so I think you don't need the USB changes.  Even if the new states 
get reintroduced bus_generic_detach() will still have to work correctly the 
way you had used it.

-- 
John Baldwin