From: utzoo!decvax!cca!obrien@RAND-UNIX@sri-unix
Newsgroups: net.unix-wizards
Title: close problem on single-use devices
Article-I.D.: sri-unix.2563
Posted: Sun Aug  8 22:07:20 1982
Received: Mon Aug  9 05:28:10 1982

Date: Thursday, 22 Jul 1982 17:43-PDT
There is a problem with devices which are single-use, when a
process which has one open dies on a signal.  It would appear that there
are cases where the close routine is not called, hence locking the device
until reboot (or mucking in /dev/kmem with adb, which amounts to the same
thing).  I believe Berkeley mentioned this, but did not have a fix.  Does
anyone out there know this symptom, and have a fix (or at least an
explanation)?  This has occurred in every version of UNIX I've ever seen,
from V6 to 4.1BSD.

	It's particularly annoying when you gradually lose all of the
"/dev/imp?" devices for talking to a network.  I've also lost the magtape
drive on occasion, though not under 4.1.  It doesn't happen every time a
process dies on a signal, just sometimes.  TTY-generated signals do not
seem to cause the problem as much as other signals.