kern/109152: [rp] RocketPort panic from device_unbusy()

[Craig Leres]

The following reply was made to PR kern/109152; it has been noted by GNATS.

From: leres at ee.lbl.gov (Craig Leres)
To: Remko Lodder <remko at elvandar.org>
Cc: freebsd-gnats-submit at FreeBSD.org
Subject: Re: kern/109152: [rp] RocketPort panic from device_unbusy() 
Date: Wed, 14 Feb 2007 00:34:11 -0800

 > This does not really feel like a bug but rather a configuration
 > failure from the administrator (you in this case).
 
 (Not a bug? Seriously?)
 
 Here's some additional info.
 
 I ran the scenario with a sio port; the system does not crash,
 /dev/modem does not go away and tip can still communicate with the
 modem after devfs is updated. (As expected.)
 
 I also ran the scenario with an puc port which worked the same as
 with the sio port.
 
 Finally, I reran the scenario with the RocketPort and found it's
 not necessary to make any changes to devfs.conf to induce a panic.
 You can simply:
 
     tip to a rocketport line
     run "/etc/rc.d/devfs restart"
     exit tip
     (wait for the system to reboot)
 
 I think the issue is a side effect of refreshing the devfs layout
 is that the state is getting reset. The rp driver seems to be the
 only one using device_busy/device_unbusy in a manner that's sensitive
 to the dev state.
 
 >                   What we need prior to continueing is a dump of
 > the panic,
 
 I used a crash dump to create the kgdb stack trace.
 
 		Craig