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SubjectRe: [PATCH] flex_array: Change behaviour on zero size allocations
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On Mon, 2011-01-31 at 09:52 +0100, Steffen Klassert wrote:
> int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
> gfp_t flags)
> {
> - int part_nr = fa_element_to_part_nr(fa, element_nr);
> + int part_nr;
> struct flex_array_part *part;
> void *dst;
>
> + if (!fa->element_size)
> + return 0;
> if (element_nr >= fa->total_nr_elements)
> return -ENOSPC;

I think this still has some of the issues of the earlier patch. The
zero-size check needs to be moved after the ->total_nr_elements check.
Otherwise, this won't produce any errors:

fa = flex_array_alloc(0, 100, GFP_KERNEL);
flex_array_put(fa, 1001, ptr, GFP_KERNEL);

> @@ -284,6 +297,8 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
> int part_nr = fa_element_to_part_nr(fa, element_nr);
> struct flex_array_part *part;
>
> + if (!fa->total_nr_elements || !fa->element_size)
> + return NULL;
> if (element_nr >= fa->total_nr_elements)
> return NULL;
> if (elements_fit_in_base(fa))

Do you really need to check fa->total_nr_elements both for zero and
against element_nr? Seems a but superfluous to me.

-- Dave



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