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SubjectRe: [PATCH] maple_tree: not necessary to filter MAPLE_PARENT_ROOT since it is not a root
Date
* Liam R. Howlett <Liam.Howlett@Oracle.com> [221115 09:29]:
> * Wei Yang <richard.weiyang@gmail.com> [221112 19:56]:
> > Root node is return at the beginning, so we are sure bit 0 is not set.
> >
> > Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> > CC: Liam R. Howlett <Liam.Howlett@Oracle.com>
> > ---
> > lib/maple_tree.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> > index 9aad98c24f3e..f8c4755e7c75 100644
> > --- a/lib/maple_tree.c
> > +++ b/lib/maple_tree.c
> > @@ -436,7 +436,7 @@ enum maple_type mte_parent_enum(struct maple_enode *p_enode,
> > return 0; /* Validated in the caller. */
> >
> > p_type &= MAPLE_NODE_MASK;
> > - p_type = p_type & ~(MAPLE_PARENT_ROOT | mte_parent_slot_mask(p_type));
> > + p_type = p_type & ~mte_parent_slot_mask(p_type);
>
> I think there is a larger cleanup that can be done here. It looks like
> mte_parent_enum() is called from one location and that location is a
> wrapper.
>
> The check for the root bit should also probably trigger a WARN_ON() and
> still return 0. I don't think the callers are doing enough to validate
> it - although they should never reach this function with a root node.
> And, in fact, I am not doing enough in the test code since I didn't
> guard this correctly in the verification of the parent slot before
> calling this function.
>
> Thanks for pointing this out. I will send out a patch to clean this up
> shortly.

On second thought, I will hold off for the 6.2 merge window for this to
go upstream.

Thanks,
Liam
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