linux-kernel - Re: [PATCH] xfs: fix returnvar.cocci warnings

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Message-ID: <20170126183056.GV9134@birch.djwong.org>
Date:   Thu, 26 Jan 2017 10:30:56 -0800
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Julia Lawall <julia.lawall@...6.fr>
Cc:     linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        kbuild-all@...org
Subject: Re: [PATCH] xfs: fix returnvar.cocci warnings

On Thu, Jan 26, 2017 at 10:20:58AM +0100, Julia Lawall wrote:
> Remove unneeded variable used to store return value.
> 
> Generated by: scripts/coccinelle/misc/returnvar.cocci
> 
> Signed-off-by: Fengguang Wu <fengguang.wu@...el.com>
> ---
> 
> Is it correct to be returning 0 in the level == 0 case?

Yes, because level == 0 is the root node for xfs dir/attr btree cursors
(which is confusing since level == 0 are leaf nodes for the regular xfs
btree cursors).  Therefore if level == 0 we're at the root and there are
no parent hash values to check.

That said, you're absolutely right that we don't need the intermediate
variable in either function.

--D

> 
>  dabtree.c |    9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> --- a/fs/xfs/scrub/dabtree.c
> +++ b/fs/xfs/scrub/dabtree.c
> @@ -96,7 +96,6 @@ xfs_scrub_da_btree_hash(
>  	struct xfs_da_node_entry	*btree;
>  	xfs_dahash_t			hash;
>  	xfs_dahash_t			parent_hash;
> -	int				error = 0;
> 
>  	/* Is this hash in order? */
>  	hash = be32_to_cpu(*hashp);
> @@ -104,7 +103,7 @@ xfs_scrub_da_btree_hash(
>  	ds->hashes[level] = hash;
> 
>  	if (level == 0)
> -		return error;
> +		return 0;
> 
>  	/* Is this hash no larger than the parent hash? */
>  	blks = ds->state->path.blk;
> @@ -112,7 +111,7 @@ xfs_scrub_da_btree_hash(
>  	parent_hash = be32_to_cpu(btree->hashval);
>  	XFS_SCRUB_DA_CHECK(ds, hash <= parent_hash);
> 
> -	return error;
> +	return 0;
>  }
> 
>  /* Scrub a da btree pointer. */
> @@ -122,12 +121,10 @@ xfs_scrub_da_btree_ptr(
>  	int				level,
>  	xfs_dablk_t			blkno)
>  {
> -	int				error = 0;
> -
>  	XFS_SCRUB_DA_CHECK(ds, blkno >= ds->lowest);
>  	XFS_SCRUB_DA_CHECK(ds, ds->highest == 0 || blkno < ds->highest);
> 
> -	return error;
> +	return 0;
>  }
> 
>  /*
> --
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