linux-kernel - [PATCH] UBIFS: use an IS_ERR test rather than a NULL test

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Date:	Tue, 30 Sep 2008 12:19:00 +0300
From:	Artem Bityutskiy <dedekind@...radead.org>
To:	linux-fsdevel@...r.kernel.org
Cc:	Adrian Hunter <ext-adrian.hunter@...ia.com>,
	linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org
Subject: [PATCH] UBIFS: use an IS_ERR test rather than a NULL test

From: Julien Brunel <brunel@...u.dk>

In case of error, the function kthread_create returns an ERR pointer,
but never returns a NULL pointer. So a NULL test that comes before an
IS_ERR test should be deleted.

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 = kthread_create(...)
... when != x = E
* if (x == NULL)
S1 else S2
// </smpl>

Signed-off-by: Julien Brunel <brunel@...u.dk>
Signed-off-by: Julia Lawall <julia@...u.dk>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
---
 fs/ubifs/super.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 667c72d..d87b0cf 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1032,8 +1032,6 @@ static int mount_ubifs(struct ubifs_info *c)
 
 		/* Create background thread */
 		c->bgt = kthread_create(ubifs_bg_thread, c, c->bgt_name);
-		if (!c->bgt)
-			c->bgt = ERR_PTR(-EINVAL);
 		if (IS_ERR(c->bgt)) {
 			err = PTR_ERR(c->bgt);
 			c->bgt = NULL;
@@ -1347,8 +1345,6 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 
 	/* Create background thread */
 	c->bgt = kthread_create(ubifs_bg_thread, c, c->bgt_name);
-	if (!c->bgt)
-		c->bgt = ERR_PTR(-EINVAL);
 	if (IS_ERR(c->bgt)) {
 		err = PTR_ERR(c->bgt);
 		c->bgt = NULL;
-- 
1.5.4.1

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