Re: RFC: radix tree safety

[Nick Piggin]

Jonathan Corbet wrote:

> I've been digging through the radix tree code, and I noticed that the
> tag functions have an interesting limitation.  The tag is given as an
> integer value, but, in reality, the only values that work are zero and
> one.  Anything else will return random results or (when setting tags)
> corrupt unrelated memory.
>
> The number of radix tree users is small, so it's not hard to confirm
> that all tag values currently in use are legal.  But the interface would
> seem to invite mistakes.
>
> The following patch puts in checks for out-of-range tag values.  I've
> elected to have the relevant call fail; one could argue that it should
> BUG instead.  Either seems better than silently doing weird stuff.  Not
> 2.6.16 material, obviously, but maybe suitable thereafter.

I'd agree if you make them BUG_ON()s.

Andrew Morton's kind of the radix-tree tags guy though... Andrew?

Nick

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