Date: Fri, 13 Jan 2006 02:19:32 -0500 From: Kris Kennaway <kris@obsecurity.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: freebsd-stable@freebsd.org Subject: Re: RELENG_6 devfs problem Message-ID: <20060113071932.GA62526@xor.obsecurity.org> In-Reply-To: <20060111210323.G28748@fledge.watson.org> References: <200601051154.32092.doconnor@gsoft.com.au> <20060111210323.G28748@fledge.watson.org>
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[-- Attachment #1 --] On Wed, Jan 11, 2006 at 09:06:32PM +0000, Robert Watson wrote: > > On Thu, 5 Jan 2006, Daniel O'Connor wrote: > > >I just installed the latest mgetty and ran it, then found it wasn't > >talking to my modem so I disabled it in /etc/ttys and killed the process. > > > >I ran fstat /dev/cuad0 to check it was dead and fstat got stuck in the > >devfs state. It seems that everything else was stuck too and now the > >machine is alive but not very functional. > > > >What can I do to try and debug it? > > Do you use devfs rule sets? I fixed a bug a week or so ago in devfs_rule.c > in HEAD, and MFC'd the fix today. The symptoms are much what you describe, > and occur when an invalid rule is proposed -- the right error is returned, > but a lock is not released resulting in it being unavailable when processes > try to access device nodes, resulting in eventual deadlock. It's > devfs_rule.c:1.21 in HEAD, and devfs_rule.c:1.14.2.3 in RELENG_6. I belive > the bug does not exist in RELENG_5, as there were significant changes in > devfs locking for 6.0, and those haven't been merged to RELENG_5. > > If this doesn't fix it, the normal debugging steps apply -- compile in DDB, > BREAK_TO_DEBUGGER, and WITNESS. When the wedge occurs, dump the lock state > (show alllocks), and we'll see if we can track down the problem. I don't use rulesets, and I encountered the same problem when using minicom to talk to serial ports. I didn't yet have time to debug it, but I can provide instructions for repeating it. Kris [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDx1SDWry0BWjoQKURAvR2AJ4h/Lhhhpda6WrVXuSof3wHTZXzGACgry3U V0qtOsHC0J/xQ4L5Q4YFAzY= =ml5h -----END PGP SIGNATURE-----
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