[PATCH net-next 14/15] ipvlan: Remove usage of list iterator variable for the loop body

[Jakob Koschel <jakobkoschel@gmail.com>]

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'.
By avoiding the use of the iterator variable after the loop, we can lower
the scope of it to the list traversal macros in the future.

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@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