linux-kernel - Re: [PATCH v2 3/4] Docs/RCU/rculist_nulls: Fix hlist

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Date:   Thu, 15 Jun 2023 17:30:00 +0000
From:   SeongJae Park <sj@...nel.org>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     SeongJae Park <sj@...nel.org>, joel@...lfernandes.org,
        mmpgouride@...il.com, corbet@....net, rcu@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] Docs/RCU/rculist_nulls: Fix hlist_head field name of 'obj'

On Wed, 14 Jun 2023 09:36:50 -0700 "Paul E. McKenney" <paulmck@...nel.org> wrote:

> On Tue, Jun 13, 2023 at 06:24:33PM +0000, SeongJae Park wrote:
> > The example code snippets on rculist_nulls.rst are assuming 'obj' to
> > have the 'hlist_head' field named 'obj_node', but a sentence is wrongly
> > mentioning 'obj->obj_node.next' as 'obj->obj_next'.  Fix it.
> > 
> > Signed-off-by: SeongJae Park <sj@...nel.org>
> > Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> > ---
> >  Documentation/RCU/rculist_nulls.rst | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/RCU/rculist_nulls.rst b/Documentation/RCU/rculist_nulls.rst
> > index 94a8bfe9f560..5cd6f3f8810f 100644
> > --- a/Documentation/RCU/rculist_nulls.rst
> > +++ b/Documentation/RCU/rculist_nulls.rst
> > @@ -86,7 +86,7 @@ Quoting Corey Minyard::
> >  2) Insertion algorithm
> >  ----------------------
> >  
> > -We need to make sure a reader cannot read the new 'obj->obj_next' value
> > +We need to make sure a reader cannot read the new 'obj->obj_node.next' value
> 
> I do like this being more specific, but if we are going do add this
> level of specificity, shouldn't we refer to a definition of ->obj_node?

Agreed, I will add the example definition in the next spin.  I also found we
would better to further fix wrong 'member' field assumption, like below:

-       ({ obj = hlist_entry(pos, typeof(*obj), member); 1; });
+       ({ obj = hlist_entry(pos, typeof(*obj), obj_node); 1; });



Thanks,
SJ

> 
> (I queued and pushed 1/4 and 2/4, thank you, and stopped here.)
> 
> 							Thanx, Paul
> 
> >  and previous value of 'obj->key'. Otherwise, an item could be deleted
> >  from a chain, and inserted into another chain. If new chain was empty
> >  before the move, 'next' pointer is NULL, and lockless reader can not
> > -- 
> > 2.25.1
> > 
>