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

[Remko Lodder]

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

From: Remko Lodder <remko at elvandar.org>
To: Craig Leres <leres at ee.lbl.gov>
Cc: freebsd-gnats-submit at FreeBSD.org
Subject: Re: kern/109152: [rp] RocketPort panic from device_unbusy()
Date: Wed, 14 Feb 2007 07:51:42 +0100

 On Tue, Feb 13, 2007 at 09:34:53PM -0800, Craig Leres wrote:
 > 
 > 	% uname -a
 > 	FreeBSD ee.lbl.gov 6.2-RELEASE FreeBSD 6.2-RELEASE #1: Mon Jan 15 11:31:32 PST 2007     leres at fox.ee.lbl.gov:/usr/src/6.2-RELEASE/sys/i386/compile/LBLSMP  i386
 > 
 > 	rp0: <RocketPort PCI> port 0x3000-0x30ff irq 19 at device 7.0 on pci2
 > 	RocketPort0 (Version 3.02) 32 ports.
 > 
 > >Description:
 > 	Removing a devfs symlink can cause a panic if a program had
 > 	that symlink open and then exits.
 > 
 > 	I use the comms/conserver port to manage a bunch of serial
 > 	lines connected to a 32 port RocketPort config. To keep
 > 	track of what each line is connected to, I create symlinks
 > 	via "link" lines in devfs.conf. I disovered that if I remove
 > 	link lines from devfs.conf, update devfs and then kill off
 > 	a conserver that has one or more of the obsolete links open,
 > 	the system will panic.
 > 
 
 Hello,
 
 This does not really feel like a bug but rather a configuration
 failure from the administrator (you in this case). When you have
 active connections, applications assume that they can have IO with
 (in this case a symlinked device). When you remove that device
 the application can no longer access that IO and in this case
 kills the system.
 
 The latter of this might be a problem (though I really feel like
 "dont do that!"): What we need prior to continueing is a dump of
 the panic, you can read how to do that on the
 http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html
 documentation pages.
 
 Thanks in advance !
 
 -- 
 Kind regards,
 
      Remko Lodder               ** remko at elvandar.org
      FreeBSD                    ** remko at FreeBSD.org
 
      /* Quis custodiet ipsos custodes */