[2392] in linux-net channel archive
Re: Internet Provider?
daemon@ATHENA.MIT.EDU (Theodore Ts'o)
Sun Apr 7 22:36:39 1996
Date: Sun, 7 Apr 1996 22:30:20 -0400
From: "Theodore Ts'o" <tytso@mit.edu>
To: linux-vger@wab-tis.rabobank.nl
Cc: linux-net@vger.rutgers.edu
In-Reply-To: Rob Janssen reading Linux mailinglist's message of Sat, 6 Apr 1996 13:26:31 +0200 (MET DST),
<m0u5W8W-0003lDC@sys3.pe1chl.ampr.org>
From: linux@pe1chl.ampr.org (Rob Janssen reading Linux mailinglist)
Date: Sat, 6 Apr 1996 13:26:31 +0200 (MET DST)
Well, my experience with device drivers (for the Z8530) is that
stability is not something achieved through experimentation and testing,
but only through careful scrutinizing of the code to make sure there are
no race conditions and all exceptions (however unlikely they are) are
properly handled.
I've done this, but this is extremely difficult, particularly in the
case of how tty hangups take place. There is a *lot* of asyncronous
processing going on. Tty processing happens at three levels: interrupt,
bottom half processing, and normal kernel level, and when you add in
network processing if you're doing PPP, that can add yet another layer.
This does indicate that some work to clean up the design is probably
necessary; the trick is trying to do this while keeping things
reasonably performant.
I do invite other people to look at the driver; they may see something
which I have missed. And I will always accept suggestions for how my
code can be improved. Just keep in mind that there is a lot of
complexity here, and simple solutions may often have unintended effects
(like a major reduction in performance!)
- Ted
