RE: n_tty.c driver patch (semantic and performance correction) (a ll recent versions)

From: Robert White <rwhite@pobox.com>
To: Ed Vance <EdV@macrolink.com>, "'rwhite@pobox.com'" <rwhite@pobox.com>
Cc: Russell King <rmk@arm.linux.org.uk>,
	"'Theodore Tso'" <tytso@mit.edu>,
	linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
	Andries Brouwer <aebr@win.tue.nl>
Subject: RE: n_tty.c driver patch (semantic and performance correction) (a ll recent versions)
Date: Tue, 30 Jul 2002 00:50:32 -0700	[thread overview]
Message-ID: <5.1.0.14.2.20020730004204.00a48da0@mail.attbi.com> (raw)
In-Reply-To: <11E89240C407D311958800A0C9ACF7D13A790E@EXCHANGE>

Yep, this is an example of "precaching" and was the example I said I have 
seen.  Since there is no USE of the precached data during the read, the 
there wasn't any demonstrable purpose to the action.

That is, this is NOT CODE "IN THE WILD", it is the contrived example of 
use, it doesn't meet the requested requirement that the example be "harmed" 
by the patch as there is no actual algorithm attached.

Any code that did this would then read this data out of the buffer by 
another request after resetting VMIN which *IS* a dependence on "magic 
state" since the current read is blocking on state that cannot be returned 
to the user.

Note that the author of the linked message says "having said that, I don't 
know of any instances where the above is employed." and then agrees the 
patch is worthwhile...

So it doesn't fulfill my request/requirement, the cited author explicitly 
supports my position, and there isn't any implication of how the rest of 
the supposed program might use this magic state...

hmmm....

Not the best argument Ed.

Rob.

At 14:46 7/29/2002 -0700, Ed Vance wrote:
>On Sat, July 27, 2002 at 7:36 PM, Robert White wrote:
> >
> > And if you could show me ONE example of wild code that would be
> > harmed by the mod I would shut up and go away.
> >
> > (I say wild code, but even contrived code would be interesting.)
>
> From the archive ...
>http://marc.theaimsgroup.com/?l=linux-kernel&m=102440556723250&w=2

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-- Rob White         --  Consider: for all vectors v, Cv - Cv = 0   --
-- rwhite@pobox.com  --    general relativity is thus disproved.    --
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-- There once was a man who claimed nothing was true,               --
--   he was later, of course, found to be lying.                    --
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