On Thu, Feb 17, 2011 at 8:19 AM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
>
> +void __put_anon_vma(struct anon_vma *anon_vma)
> +{
> + if (anon_vma->root != anon_vma)
> + put_anon_vma(anon_vma->root);
> + anon_vma_free(anon_vma);
> }
So this makes me nervous. It looks like recursion.
Now, I don't think we can ever get a chain of these things (because
the root should be the root of everything), but I still preferred the
older code that made that "one-level root" case explicit, and didn't
have recursion.
IOW, even though it should be entirely equivalent, I think I'd really
prefer something like
void __put_anon_vma(struct anon_vma *anon_vma)
{
struct anon_vma *root = anon_vma->root;
if (root != anon_vma && atomic_dec_and_test(&root->refcount))
anon_vma_free(root);
anon_vma_free(anon_vma);
}
instead. Exactly because it makes it very clear that the "root" is a
root, and we're not doing some possibly arbitrarily deep list like the
dentry tree (which avoids recursion by open-coding its freeing as a
loop).
Hmm? (The above is obviously untested, maybe it has some stupid bug)
Linus
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