Re: [PATCH][TRIVIAL] Bugzilla bug # 322 - double logical operator drivers/char/sx.c

From: jw schultz (jw@pegasys.ws)
Date: Thu Aug 07 2003 - 18:02:52 EST

On Thu, Aug 07, 2003 at 04:20:37AM -0400, Jeff Sipek wrote:
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> On Wednesday 06 August 2003 20:35, Timothy Miller wrote:
> > Josef 'Jeff' Sipek wrote:
> > > Just a simple fix to make the statements more readable. (instead of
> > > "i < TIMEOUT > 0" the statement is divided into two, joined by &&.)
> >
> > Can you really DO (x < y > z) and have it work as an anded pair of
> > comparisons? Maybe this is an addition to C that I am not aware of.
> >
> > I would expect (x < y > z) to be equivalent to ((x < y) > z).
>
> Odd, this has been in the kernel ever since Linus started using BK. I didn't
> check pre-BK. I wonder what the author intended to say. (I believe in the
> ((a<b) && (b>c)) theory.)

I've got an old system with 2.2.10 and took a look. It
appears as though the form of the loop in may of 1999 was

        for(delay = SX_CCR_TIMEOUT; delay; delay--)

so my guess is that the changes were made around the
constant to minimise typing and progressed something like so:

        for(delay = SX_CCR_TIMEOUT; delay; delay--)
        for(delay = SX_CCR_TIMEOUT; delay > 0; delay--)
        for(delay = 0; delay < SX_CCR_TIMEOUT > 0; delay++)

with name changes somewhere in the mix. So there was never
any intent to have a double test. Besides comparing a
constant with another constant wouldn't make much sense. 

-- 
________________________________________________________________
	J.W. Schultz            Pegasystems Technologies
	email address:		jw@pegasys.ws

		Remember Cernan and Schmitt
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