Re: [Ext2-devel] Re: [PATCH] use-before-uninitialized value in ext3(2)_find_ goal

[Chris Wright]

* Matthew Wilcox (willy@xxxxxxxxxx) wrote:
> On Wed, May 19, 2004 at 12:53:28PM -0700, Chris Wright wrote:
> > I know it's a slightly bigger patch, but would it make sense to just enforce
> > this as part of api?  Just a thought...(patch untested)
> 
> No, that doesn't work.  Look:
> 
> reread:
> 	...
> 
>         if (ext2_find_goal(inode, iblock, chain, partial, &goal) < 0)
>                 goto changed;
> 
> changed:
>         while (partial > chain) {
>                 brelse(partial->bh);
>                 partial--;
>         }
>         goto reread;
> 
> So it's spaghetti code that can modify goal.  Yuck.
> 
> 5 labels in one function?  3 backwards jumps?  Disgusting.

Heh, yeah.  I actually did look, and had the same concern about goal.
I think it's ok though.  For one thing, in that changed->reread loop
goal is never used.  Secondly, I think that the intention was to have
*_find_goal start from 0, not from last goal, since goal is marked as
output, and Mingming's patch reset goal to 0 every pass through.  This
is exactly why I thought it useful to clarify the api.

thanks,
-chris
-- 
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