linux-kernel - [PATCH net-next v5 17/18] ipvlan: Remove usage of list iterator variable for the loop body

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Message-Id: <20220427160635.420492-18-jakobkoschel@gmail.com>
Date:   Wed, 27 Apr 2022 18:06:34 +0200
From:   Jakob Koschel <jakobkoschel@...il.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        Steen Hegelund <Steen.Hegelund@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Ariel Elior <aelior@...vell.com>,
        Manish Chopra <manishc@...vell.com>,
        Edward Cree <ecree.xilinx@...il.com>,
        Martin Habets <habetsm.xilinx@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Jiri Pirko <jiri@...nulli.us>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Casper Andersson <casper.casan@...il.com>,
        Jakob Koschel <jakobkoschel@...il.com>,
        Arnd Bergmann <arnd@...db.de>, Jason Gunthorpe <jgg@...pe.ca>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Colin Ian King <colin.king@...el.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Xu Wang <vulab@...as.ac.cn>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, bpf@...r.kernel.org,
        Mike Rapoport <rppt@...nel.org>,
        "Brian Johannesmeyer" <bjohannesmeyer@...il.com>,
        Cristiano Giuffrida <c.giuffrida@...nl>,
        "Bos, H.J." <h.j.bos@...nl>
Subject: [PATCH net-next v5 17/18] ipvlan: Remove usage of list iterator variable for the loop body

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@...il.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