Re: [PATCH] xfs: fix unused variable warning in xfs_buf_item_unlock()

[Brian Foster <bfoster@redhat.com>]

On Fri, Sep 01, 2017 at 07:52:09AM +1000, Dave Chinner wrote:
> On Thu, Aug 31, 2017 at 09:41:07AM -0700, Darrick J. Wong wrote:
> > On Thu, Aug 31, 2017 at 12:04:58PM -0400, Brian Foster wrote:
> > > The ordered variable generates an unused warning on !DEBUG builds.
> > > Separate the initialization of the associated variables from the
> > > declarations to quiet gcc.
> > > 
> > > Signed-off-by: Brian Foster <bfoster@redhat.com>
> > 
> > Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> And merged before everyone in different timezones has had a chance
> to comment. :(
> 
> I just built the latest for-next with CONFIG_XFS_DEBUG=n and there's
> three set-but-unused warnings, one of which is introduced by this
> patch.
> 
> fs/xfs/libxfs/xfs_inode_fork.c: In function ¿xfs_iext_realloc_indirect¿:
> fs/xfs/libxfs/xfs_inode_fork.c:1503:7: error: variable ¿size¿ set but not used [-Werror=unused-but-set-variable]
>   int  size;  /* current indirection array size */
>        ^~~~
> 
> fs/xfs/xfs_buf_item.c: In function ¿xfs_buf_item_unlock¿:
> fs/xfs/xfs_buf_item.c:573:9: error: variable ¿ordered¿ set but not used [-Werror=unused-but-set-variable]
>   bool   ordered;
>          ^~~~~~~
> 
> fs/xfs/xfs_log_recover.c: In function ¿xlog_recover_process_intents¿:
> fs/xfs/xfs_log_recover.c:4830:13: error: variable ¿last_lsn¿ set but not used [-Werror=unused-but-set-variable]
>   xfs_lsn_t  last_lsn;
>              ^~~~~~~~
> 
> Yeah, maintainer habits die hard; I'm still patching fs/xfs/Makefile
> in my build trees with this:
> 
> -ccflags-y += -I$(src)                  # needed for trace events
> +ccflags-y += -I$(src) -Werror -Wunused-but-set-variable
> 
> Which catches stupid problems like this that will the userspace
> libxfs build will trip over when the next merge occurs.
> 

Note that the associated bli code is not shared with userspace, fwiw. We
should probably fix the warnings regardless...

Hmm, I don't see that option enabled in xfsprogs. Is the issue then that
it is more of a default behavior and the kernel disables it somewhere?
After poking around a bit, that appears to be the case. We can run 'make
W=1' to generate these (and more) in the kernel build.

Brian

> Playing games with declaration/initialisation order to avoid
> warnigns just doesn't work.
> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com
> --
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