Re: [PATCH 7/9] maple_tree: Delete redundant code in mas_next_node()

[Peng Zhang]

在 2023/4/26 00:45, Liam R. Howlett 写道:
> * Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx> [230425 07:05]:
>
> The title of the patch seems wrong.
>
> This isn't redundant code and you aren't deleting it.. you are moving a
> block of code outside a loop.  You did modify the check though, is that
> the redundant code?
>
> > When offset == node_end is satisfied, go to the parent node, mas->max
> > will not change. So there is no need to update min on the move.
> Please try not to state the code in your commit message.
>
> I have moved this block of code in patch 27/34 [1]
>
> > Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
> > ---
> >   lib/maple_tree.c | 7 ++-----
> >   1 file changed, 2 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> > index 83441ef2e1f57..8bfa837b7b752 100644
> > --- a/lib/maple_tree.c
> > +++ b/lib/maple_tree.c
> > @@ -4616,7 +4616,8 @@ static inline int mas_next_node(struct ma_state *mas, struct maple_node *node,
> >   	enum maple_type mt;
> >   	void __rcu **slots;
> >   
> > -	if (mas->max >= max)
> > +	min = mas->max + 1;
> > +	if (min > max)
> >   		goto no_entry;
> What happens on overflow?
Yes, I made a mistake.
I will drop this patch since you have updated the code in patch 27/34.
> >   
> >   	level = 0;
> > @@ -4624,10 +4625,6 @@ static inline int mas_next_node(struct ma_state *mas, struct maple_node *node,
> >   		if (ma_is_root(node))
> >   			goto no_entry;
> >   
> > -		min = mas->max + 1;
> > -		if (min > max)
> > -			goto no_entry;
> > -
> >   		if (unlikely(mas_ascend(mas)))
> >   			return 1;
> >   
> > --
> > 2.20.1
> [1] https://lore.kernel.org/linux-mm/20230425140955.3834476-28-Liam.Howlett@xxxxxxxxxx/