linux-kernel - Re: [PATCH] xfs: Remove unused function

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Date:   Sat, 11 Nov 2023 09:39:34 -0600
From:   Eric Sandeen <sandeen@...deen.net>
To:     "Darrick J. Wong" <djwong@...nel.org>,
        Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
Cc:     Bill O'Donnell <bodonnel@...hat.com>, chandan.babu@...cle.com,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Abaci Robot <abaci@...ux.alibaba.com>
Subject: Re: [PATCH] xfs: Remove unused function

On 11/7/23 2:44 PM, Darrick J. Wong wrote:
> On Tue, Nov 07, 2023 at 01:26:46PM -0600, Bill O'Donnell wrote:
>> On Fri, Nov 03, 2023 at 03:30:40PM +0800, Jiapeng Chong wrote:
>>> The function are defined in the bitmap.c file, but not called
>>> elsewhere, so delete the unused function.
>>>
>>> fs/xfs/scrub/bitmap.c:55:1: warning: unused function 'xbitmap_tree_iter_next'.
>>>
>>> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
>>> Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7137
>>> Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
>>
>> Makes sense.
>> Reviewed-by: Bill O'Donnell <bodonnel@...hat.com>
> 
> I disagree -- I added redundant forward declarations here so I wouldn't
> have to go digging through the 150LOC definition of INTERVAL_TREE_DEFINE
> to figure out what helper functions were actually being defined by the
> macro.  They'll trigger compiler errors if the definition of
> INTERVAL_TREE_DEFINE ever drifts away from my understanding of it at the
> time I wrote the code.

And the comment above those declarations say as much, but Jiapeng Chong seems to
be getting a legitimate warning as a result, and AFAICT xbitmap_tree_iter_next
really isn't used in the codebase. Maybe it's worth commenting it out or
#ifdefing it, while leaving it around for reference as you intended?

(I'm sympathetic to the macro-generated function hell, for sure.)

-Eric

> --D
> 
>>
>>
>>> ---
>>>  fs/xfs/scrub/bitmap.c | 4 ----
>>>  1 file changed, 4 deletions(-)
>>>
>>> diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
>>> index e0c89a9a0ca0..ba4b18e40faa 100644
>>> --- a/fs/xfs/scrub/bitmap.c
>>> +++ b/fs/xfs/scrub/bitmap.c
>>> @@ -48,10 +48,6 @@ static inline struct xbitmap_node *
>>>  xbitmap_tree_iter_first(struct rb_root_cached *root, uint64_t start,
>>>  			uint64_t last);
>>>  
>>> -static inline struct xbitmap_node *
>>> -xbitmap_tree_iter_next(struct xbitmap_node *node, uint64_t start,
>>> -		       uint64_t last);
>>> -
>>>  INTERVAL_TREE_DEFINE(struct xbitmap_node, bn_rbnode, uint64_t,
>>>  		__bn_subtree_last, START, LAST, static inline, xbitmap_tree)
>>>  
>>> -- 
>>> 2.20.1.7.g153144c
>>>
>>
>