linux-kernel - [PATCH 2/2] drivers/mtd/ubi: Eliminate update of list_for_each

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Date:	Sat, 7 Aug 2010 11:09:29 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	Artem Bityutskiy <dedekind1@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH 2/2] drivers/mtd/ubi: Eliminate update of list_for_each_entry
 loop cursor

From: Julia Lawall <julia@...u.dk>

list_for_each_entry uses its first argument to move from one element to the
next, so modifying it can break the iteration.  The variable re1 is already
used within the loop as a temporary variable, and is not live here.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r@
iterator name list_for_each_entry;
expression x,E;
position p1,p2;
@@

list_for_each_entry@p1(x,...) { <... x =@p2 E ...> }

@@
expression x,E;
position r.p1,r.p2;
statement S;
@@

*x =@p2 E
...
list_for_each_entry@p1(x,...) S
// </smpl>

Signed-off-by: Julia Lawall <julia@...u.dk>

---
 drivers/mtd/ubi/cdev.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 4dfa6b9..3d2d1a6 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -798,18 +798,18 @@ static int rename_volumes(struct ubi_device *ubi,
 			goto out_free;
 		}
 
-		re = kzalloc(sizeof(struct ubi_rename_entry), GFP_KERNEL);
-		if (!re) {
+		re1 = kzalloc(sizeof(struct ubi_rename_entry), GFP_KERNEL);
+		if (!re1) {
 			err = -ENOMEM;
 			ubi_close_volume(desc);
 			goto out_free;
 		}
 
-		re->remove = 1;
-		re->desc = desc;
-		list_add(&re->list, &rename_list);
+		re1->remove = 1;
+		re1->desc = desc;
+		list_add(&re1->list, &rename_list);
 		dbg_msg("will remove volume %d, name \"%s\"",
-			re->desc->vol->vol_id, re->desc->vol->name);
+			re1->desc->vol->vol_id, re1->desc->vol->name);
 	}
 
 	mutex_lock(&ubi->device_mutex);
--
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