linux-kernel - Re: [PATCH 06/10] maple_tree: Wrap the replace operation with an inline function.

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Date:   Tue, 16 May 2023 10:16:26 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Peng Zhang <zhangpeng.00@...edance.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, maple-tree@...ts.infradead.org
Subject: Re: [PATCH 06/10] maple_tree: Wrap the replace operation with an
 inline function.

* Peng Zhang <zhangpeng.00@...edance.com> [230515 20:46]:
> 
> 
> 在 2023/5/16 01:07, Liam R. Howlett 写道:
> > * Peng Zhang <zhangpeng.00@...edance.com> [230515 09:18]:
> > > To make mas_wr_modify() cleaner, wrap the replace operation with an
> > > inline function.
> > 
> > mas_wr_modify() is already pretty small.  Is there any reason you want
> > this in its own function besides it looking cleaner?
> I just want to make the four fast paths in mas_wr_modify()
> look uniform without any functional effect.

I'd like to keep it the way it is. I think the comment stating what is
going on is clear enough and mas_wr_modify() isn't too big.

> > 
> > > 
> > > Signed-off-by: Peng Zhang <zhangpeng.00@...edance.com>
> > > ---
> > >   lib/maple_tree.c | 21 +++++++++++++++------
> > >   1 file changed, 15 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> > > index 4c649d75a4923..ce695adc670ec 100644
> > > --- a/lib/maple_tree.c
> > > +++ b/lib/maple_tree.c
> > > @@ -4288,6 +4288,19 @@ static inline void mas_wr_extend_null(struct ma_wr_state *wr_mas)
> > >   	}
> > >   }
> > > +static inline bool mas_wr_replace(struct ma_wr_state *wr_mas)
> > > +{
> > > +	struct ma_state *mas = wr_mas->mas;
> > > +
> > > +	if (wr_mas->r_min == mas->index && wr_mas->r_max == mas->last) {
> > > +		rcu_assign_pointer(wr_mas->slots[mas->offset], wr_mas->entry);
> > > +		if (!!wr_mas->entry ^ !!wr_mas->content)
> > > +			mas_update_gap(mas);
> > > +		return true;
> > > +	}
> > > +	return false;
> > > +}
> > > +
> > >   static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
> > >   {
> > >   	unsigned char end = wr_mas->node_end;
> > > @@ -4347,13 +4360,9 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas)
> > >   	unsigned char node_size;
> > >   	struct ma_state *mas = wr_mas->mas;
> > > -	/* Direct replacement */
> > > -	if (wr_mas->r_min == mas->index && wr_mas->r_max == mas->last) {
> > > -		rcu_assign_pointer(wr_mas->slots[mas->offset], wr_mas->entry);
> > > -		if (!!wr_mas->entry ^ !!wr_mas->content)
> > > -			mas_update_gap(mas);
> > > +	/* Attempt to direct replace */
> > > +	if (mas_wr_replace(wr_mas))
> > >   		return;
> > > -	}
> > >   	/* Attempt to append */
> > >   	node_slots = mt_slots[wr_mas->type];
> > > -- 
> > > 2.20.1
> > >