[Ocfs2-devel] [PATCH 1/2] fs/ocfs2/dlm: Eliminate update of list_for_each_entry loop cursor

[Julia Lawall]

From: Julia Lawall <julia at diku.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 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 at p1(x,...) { <... x =@p2 E ...> }

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

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

Signed-off-by: Julia Lawall <julia at diku.dk>

---
I don't know whether this is the right solution, but it seems plausible
considering the subsequent test on lock.  In any case, setting lock to NULL
and then going back to the top of the loop does not work.

 fs/ocfs2/dlm/dlmrecovery.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 9dfaac7..7084a11 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -1792,10 +1792,10 @@ static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
 			for (j = DLM_GRANTED_LIST; j <= DLM_BLOCKED_LIST; j++) {
 				tmpq = dlm_list_idx_to_ptr(res, j);
 				list_for_each_entry(lock, tmpq, list) {
-					if (lock->ml.cookie != ml->cookie)
+					if (lock->ml.cookie != ml->cookie) {
 						lock = NULL;
-					else
 						break;
+					}
 				}
 				if (lock)
 					break;