linux-kernel - Re: lib/maple_tree.c:330:20: error: unused function 'mte_set

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Message-ID: <20240831012845.GA2993938@thelio-3990X>
Date: Fri, 30 Aug 2024 18:28:45 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: kernel test robot <lkp@...el.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, llvm@...ts.linux.dev,
	oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Linux Memory Management List <linux-mm@...ck.org>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>
Subject: Re: lib/maple_tree.c:330:20: error: unused function 'mte_set_full'

On Fri, Aug 30, 2024 at 05:50:15PM -0700, Andrew Morton wrote:
> On Sat, 31 Aug 2024 07:42:38 +0800 kernel test robot <lkp@...el.com> wrote:
> 
> > All errors (new ones prefixed by >>):
> > 
> > >> lib/maple_tree.c:330:20: error: unused function 'mte_set_full' [-Werror,-Wunused-function]
> >      330 | static inline void mte_set_full(const struct maple_enode *node)
> >          |                    ^~~~~~~~~~~~
> > >> lib/maple_tree.c:335:20: error: unused function 'mte_clear_full' [-Werror,-Wunused-function]
> >      335 | static inline void mte_clear_full(const struct maple_enode *node)
> >          |                    ^~~~~~~~~~~~~~
> >    2 errors generated.
> 
> afaict these have never been used.  It's odd that this was just detected.

I don't think it has just now been detected, as these functions have
been flagged before:

https://lore.kernel.org/20240503160821.GB3960118@thelio-3990X/

> Should we just zap them or is there some reason to retain?

>From the above thread, Liam and Matthew seem to want to retain them.
Perhaps just wrapping them in '#if 0' and a comment that says these will
eventually see use would be a happy compromise between outright removal
and doing nothing about this warning?

> --- a/lib/maple_tree.c~a
> +++ a/lib/maple_tree.c
> @@ -348,21 +348,6 @@ static inline void *mte_safe_root(const
>  	return (void *)((unsigned long)node & ~MAPLE_ROOT_NODE);
>  }
>  
> -static inline void *mte_set_full(const struct maple_enode *node)
> -{
> -	return (void *)((unsigned long)node & ~MAPLE_ENODE_NULL);
> -}
> -
> -static inline void *mte_clear_full(const struct maple_enode *node)
> -{
> -	return (void *)((unsigned long)node | MAPLE_ENODE_NULL);
> -}
> -
> -static inline bool mte_has_null(const struct maple_enode *node)
> -{
> -	return (unsigned long)node & MAPLE_ENODE_NULL;
> -}
> -
>  static __always_inline bool ma_is_root(struct maple_node *node)
>  {
>  	return ((unsigned long)node->parent & MA_ROOT_PARENT);
> _
> 
> 
>