netdev - Re: removing gotos considered harmful...

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Date:	Thu, 04 Jan 2007 11:35:29 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	gerrit@....abdn.ac.uk (Gerrit Renker)
Cc:	davem@...emloft.net, netdev@...r.kernel.org, arnaldo.melo@...il.com
Subject: Re: removing gotos considered harmful...

Gerrit Renker <gerrit@....abdn.ac.uk> wrote:
> 
>                        size = 0;
>                        sk_for_each(sk2, node, list)
>                                if (++size >= best_size_so_far)
>                                        goto next;
>                        best_size_so_far = size;
>                        best = result;
>                next:;
> 
>  
> |  and this got converted into:
> |  
> |                       sk_for_each(sk2, node, head)
> |                               if (++size < best_size_so_far) {
> |                                       best_size_so_far = size;
> |                                       best = result;
> |                               }
> |  
> |  Which does something very very different from the original.
> ===> Sorry, I fail to see where the two differ. They have the same postcondition
>     upon loop exit; sk2, node, size, and head are not referenced anywhere in the 
>     code that follows.

They're different because the former only updates best_size_so_far
after termination while the latter does it from the start.  It's
like moving the goal-posts while someone's trying to shoot :)

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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