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From:   Jakob Koschel <jakobkoschel@gmail.com>
To:     "David S. Miller" <davem@davemloft.net>
Cc:     Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        Lars Povlsen <lars.povlsen@microchip.com>,
        Steen Hegelund <Steen.Hegelund@microchip.com>,
        UNGLinuxDriver@microchip.com, Ariel Elior <aelior@marvell.com>,
        Manish Chopra <manishc@marvell.com>,
        Edward Cree <ecree.xilinx@gmail.com>,
        Martin Habets <habetsm.xilinx@gmail.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Jiri Pirko <jiri@resnulli.us>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Casper Andersson <casper.casan@gmail.com>,
        Bjarni Jonasson <bjarni.jonasson@microchip.com>,
        Jakob Koschel <jakobkoschel@gmail.com>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Arnd Bergmann <arnd@arndb.de>,
        Colin Ian King <colin.king@intel.com>,
        Eric Dumazet <edumazet@google.com>,
        Xu Wang <vulab@iscas.ac.cn>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linuxppc-dev@lists.ozlabs.org, bpf@vger.kernel.org,
        Mike Rapoport <rppt@kernel.org>,
        "Brian Johannesmeyer" <bjohannesmeyer@gmail.com>,
        Cristiano Giuffrida <c.giuffrida@vu.nl>,
        "Bos, H.J." <h.j.bos@vu.nl>
Subject: [PATCH net-next v4 17/18] ipvlan: Remove usage of list iterator variable for the loop body
Date:   Fri, 15 Apr 2022 14:29:46 +0200
Message-Id: <20220415122947.2754662-18-jakobkoschel@gmail.com>
In-Reply-To: <20220415122947.2754662-1-jakobkoschel@gmail.com>
References: <20220415122947.2754662-1-jakobkoschel@gmail.com>
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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@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