Path: utzoo!utgpu!watmath!clyde!att!pacbell!ditka!rpp386!jfh
From: jfh@rpp386.Dallas.TX.US (The Beach Bum)
Newsgroups: comp.unix.wizards
Subject: Re: Ultrix tape job is unkillable!
Summary: alternate wakeups.
Message-ID: <10089@rpp386.Dallas.TX.US>
Date: 19 Dec 88 02:59:31 GMT
References: <476@larry.UUCP> <43200057@uicsrd.csrd.uiuc.edu> <1988Dec18.023931.28730@utzoo.uucp>
Reply-To: jfh@rpp386.Dallas.TX.US (The Beach Bum)
Organization: Big "D" Home for Wayward Hackers
Lines: 22

In article <1988Dec18.023931.28730@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
>Many, many device drivers unfortunately don't observe a general rule of
>robustness:  unless there is legitimate reason for a device operation to
>take an unbounded time to complete (e.g. a read from a terminal), drivers
>should *never* sleep waiting for a device without setting a timeout.

Or as a minimum, provide a means of awakening a wedged driver.  Perhaps
by using a single event and checking for error conditions or completion
prior to sleeping or continuing.

>This applies to *all* devices, since hardware failures should be handled
>more gracefully than by just hanging, but devices that can wander off into
>limbo due to human intervention are particularly important cases.

And as a suggestion - the inclusion of an ioctl to RESET the device
has proven most helpful with a certain vendors hardware which is highly
prone to extreme flakyness.
-- 
John F. Haugh II                        +-Quote of the Week:-------------------
VoiceNet: (214) 250-3311   Data: -6272  |"Just remember, if you swap the first
InterNet: jfh@rpp386.Dallas.TX.US       | and second letters of USENET you get
UucpNet : <backbone>!killer!rpp386!jfh  +-SUENET."      -- J. F. Haugh II------