[PATCH net-next v2 17/18] ipvlan: Remove usage of list iterator variable for the loop body

[Jakob Koschel]

In preparation to limit the scope of the list iterator variable to the
list traversal loop, use a dedicated pointer to iterate through the
list [1].

Since that variable should not be used past the loop iteration, a
separate variable is used to 'remember the current location within the
loop'.

To either continue iterating from that position or start a new
iteration (if the previous iteration was complete) list_prepare_entry()
is used.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel at gmail.com>
---
 drivers/net/ipvlan/ipvlan_main.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 696e245f6d00..063d7c30e944 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -9,7 +9,7 @@
 static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 				struct netlink_ext_ack *extack)
 {
-	struct ipvl_dev *ipvlan;
+	struct ipvl_dev *ipvlan, *tmp = NULL;
 	unsigned int flags;
 	int err;
 
@@ -26,8 +26,10 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 						       flags & ~IFF_NOARP,
 						       extack);
 			}
-			if (unlikely(err))
+			if (unlikely(err)) {
+				tmp = ipvlan;
 				goto fail;
+			}
 		}
 		if (nval == IPVLAN_MODE_L3S) {
 			/* New mode is L3S */
@@ -43,6 +45,7 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 	return 0;
 
 fail:
+	ipvlan = list_prepare_entry(tmp, &port->ipvlans, pnode);
 	/* Undo the flags changes that have been done so far. */
 	list_for_each_entry_continue_reverse(ipvlan, &port->ipvlans, pnode) {
 		flags = ipvlan->dev->flags;
-- 
2.25.1