[Cluster-devel] [PATCH 1/2] dlm: remove usage of list iterator for list_add() after the loop body

[Jakob Koschel <jakobkoschel@gmail.com>]

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Before, the code implicitly used the head when no element was found
when using &pos->list. Since the new variable is only set if an
element was found, the list_add() is performed within the loop
and only done after the loop if it is done on the list head directly.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w at mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
 fs/dlm/lock.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index bdb51d209ba2..66e92617d7ea 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -1306,13 +1306,17 @@ static inline void unhold_lkb(struct dlm_lkb *lkb)
 static void lkb_add_ordered(struct list_head *new, struct list_head *head,
 			    int mode)
 {
-	struct dlm_lkb *lkb = NULL;
+	struct dlm_lkb *lkb = NULL, *iter;
 
-	list_for_each_entry(lkb, head, lkb_statequeue)
-		if (lkb->lkb_rqmode < mode)
+	list_for_each_entry(iter, head, lkb_statequeue)
+		if (iter->lkb_rqmode < mode) {
+			lkb = iter;
+			list_add_tail(new, &iter->lkb_statequeue);
 			break;
+		}
 
-	__list_add(new, lkb->lkb_statequeue.prev, &lkb->lkb_statequeue);
+	if (!lkb)
+		list_add_tail(new, head);
 }
 
 /* add/remove lkb to rsb's grant/convert/wait queue */

base-commit: f82da161ea75dc4db21b2499e4b1facd36dab275
-- 
2.25.1