linux-kernel - Re: [PROBLEM linux-next] fs/reiserfs/do_balan.c:1147:13: error: variable ‘leaf_mi’ set but not used [-Werror=unused-but-set-variable]

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Message-ID: <20240717154434.jba66jupaf566tes@quack3>
Date: Wed, 17 Jul 2024 17:44:34 +0200
From: Jan Kara <jack@...e.cz>
To: Mirsad Todorovac <mtodorovac69@...il.com>
Cc: Jan Kara <jack@...e.cz>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Kees Cook <kees@...nel.org>, Christian Brauner <brauner@...nel.org>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Al Viro <viro@...iv.linux.org.uk>, Jeff Layton <jlayton@...nel.org>,
	reiserfs-devel@...r.kernel.org
Subject: Re: [PROBLEM linux-next] fs/reiserfs/do_balan.c:1147:13: error: variable ‘leaf_mi’ set but not used [-Werror=unused-but-set-variable]

On Tue 16-07-24 19:17:05, Mirsad Todorovac wrote:
> On 7/15/24 19:28, Jan Kara wrote:
> > Hello Mirsad!
> > 
> > On Wed 10-07-24 20:09:27, Mirsad Todorovac wrote:
> >> On the linux-next vanilla next-20240709 tree, I have attempted the seed KCONFIG_SEED=0xEE7AB52F
> >> which was known from before to trigger various errors in compile and build process.
> >>
> >> Though this might seem as contributing to channel noise, Linux refuses to build this config,
> >> treating warnings as errors, using this build line:
> >>
> >> $ time nice make W=1 -k -j 36 |& tee ../err-next-20230709-01a.log; date
> >>
> >> As I know that the Chief Penguin doesn't like warnings, but I am also aware that there are plenty
> >> left, there seems to be more tedious work ahead to make the compilers happy.
> >>
> >> The compiler output is:
> >>
> >> ---------------------------------------------------------------------------------------------------------
> >> fs/reiserfs/do_balan.c: In function ‘balance_leaf_new_nodes_paste_whole’:
> >> fs/reiserfs/do_balan.c:1147:13: error: variable ‘leaf_mi’ set but not used [-Werror=unused-but-set-variable]
> >>  1147 |         int leaf_mi;
> >>       |             ^~~~~~~
> > 
> > Frankly, I wouldn't bother with reiserfs. The warning is there for ages,
> > the code is going to get removed in two releases, so I guess we can live
> > with these warnings for a few more months...
> 
> In essence I agree with you, but for sentimental reasons I would like to
> keep it because it is my first journaling Linux system on Knoppix 🙂

As much as I understand your sentiment (I have a bit of history with that
fs as well) the maintenance cost isn't really worth it and most fs folks
will celebrate when it's removed. We have already announced the removal
year and half ago and I'm fully for executing that plan at the end of this
year.

> Patch is also simple and a no-brainer, as proposed by Mr. Cook:
> 
> -------------------------------><------------------------------------------
> diff --git a/fs/reiserfs/do_balan.c b/fs/reiserfs/do_balan.c
> index 5129efc6f2e6..fbe73f267853 100644
> --- a/fs/reiserfs/do_balan.c
> +++ b/fs/reiserfs/do_balan.c
> @@ -1144,7 +1144,9 @@ static void balance_leaf_new_nodes_paste_whole(struct tree_balance *tb,
>  {
>  	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
>  	int n = B_NR_ITEMS(tbS0);
> +#ifdef CONFIG_REISERFS_CHECK
>  	int leaf_mi;
> +#endif

Well, I would not like this even for actively maintained code ;) If you
want to silence these warnings in this dead code, then I could live with
something like:

#if defined( CONFIG_REISERFS_CHECK )
#define RFALSE(cond, format, args...) __RASSERT(!(cond), ....)
#else
- #define RFALSE( cond, format, args... ) do {;} while( 0 )
+ #define RFALSE( cond, format, args... ) do { (void)cond; } while( 0 )
#endif

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR