[PATCH] fs/gfs2: Use an IS_ERR test rather than a NULL test

[PATCH] fs/gfs2: Use an IS_ERR test rather than a NULL test

[Julien Brunel]

From: Julien Brunel <brunel@diku.dk>

In case of error, the function gfs2_inode_lookup returns an
ERR pointer, but never returns a NULL pointer. So a NULL test that
necessarily comes after an IS_ERR test should be deleted, and a NULL
test that may come after a call to this function should be
strengthened by an IS_ERR test.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@match_bad_null_test@
expression x, E;
statement S1,S2;
@@
x = gfs2_inode_lookup(...)
... when != x = E
* if (x != NULL) 
S1 else S2
// </smpl>

Signed-off-by:  Julien Brunel <brunel@diku.dk>
Signed-off-by:  Julia Lawall <julia@diku.dk>

---
 fs/gfs2/inode.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff -u -p a/fs/gfs2/inode.c b/fs/gfs2/inode.c
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -1033,13 +1033,11 @@ struct inode *gfs2_createi(struct gfs2_h
 
 	if (bh)
 		brelse(bh);
-	if (!inode)
-		return ERR_PTR(-ENOMEM);
 	return inode;
 
 fail_gunlock2:
 	gfs2_glock_dq_uninit(ghs + 1);
-	if (inode)
+	if (inode && !IS_ERR(inode))
 		iput(inode);
 fail_gunlock:
 	gfs2_glock_dq(ghs);

Re: [PATCH] fs/gfs2: Use an IS_ERR test rather than a NULL test

[steve]

Hi,

Sorry for taking so long about this. Its now in the -nmw git tree.
Thanks,

Steve.

On Mon, Sep 01, 2008 at 10:51:22AM +0200, Julien Brunel wrote:
> From: Julien Brunel <brunel@diku.dk>
> 
> In case of error, the function gfs2_inode_lookup returns an
> ERR pointer, but never returns a NULL pointer. So a NULL test that
> necessarily comes after an IS_ERR test should be deleted, and a NULL
> test that may come after a call to this function should be
> strengthened by an IS_ERR test.
> 
> The semantic match that finds this problem is as follows:
> (http://www.emn.fr/x-info/coccinelle/)
> 
> // <smpl>
> @match_bad_null_test@
> expression x, E;
> statement S1,S2;
> @@
> x = gfs2_inode_lookup(...)
> ... when != x = E
> * if (x != NULL) 
> S1 else S2
> // </smpl>
> 
> Signed-off-by:  Julien Brunel <brunel@diku.dk>
> Signed-off-by:  Julia Lawall <julia@diku.dk>
> 
> ---
>  fs/gfs2/inode.c |    4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff -u -p a/fs/gfs2/inode.c b/fs/gfs2/inode.c
> --- a/fs/gfs2/inode.c
> +++ b/fs/gfs2/inode.c
> @@ -1033,13 +1033,11 @@ struct inode *gfs2_createi(struct gfs2_h
>  
>  	if (bh)
>  		brelse(bh);
> -	if (!inode)
> -		return ERR_PTR(-ENOMEM);
>  	return inode;
>  
>  fail_gunlock2:
>  	gfs2_glock_dq_uninit(ghs + 1);
> -	if (inode)
> +	if (inode && !IS_ERR(inode))
>  		iput(inode);
>  fail_gunlock:
>  	gfs2_glock_dq(ghs);
> --
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