linux-kernel - [PATCH net-next v2 18/18] team: Remove use of list iterator variable for list_for_each_entry

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Date:   Tue, 12 Apr 2022 12:58:30 +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>,
        Colin Ian King <colin.king@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Michael Walle <michael@...le.cc>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        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 v2 18/18] team: Remove use of list iterator variable for list_for_each_entry_from()

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 skip the 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/team/team.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index b07dde6f0abf..688c4393f099 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -2425,17 +2425,17 @@ static int team_nl_send_options_get(struct team *team, u32 portid, u32 seq,
 				    int flags, team_nl_send_func_t *send_func,
 				    struct list_head *sel_opt_inst_list)
 {
+	struct team_option_inst *opt_inst, *tmp = NULL;
 	struct nlattr *option_list;
 	struct nlmsghdr *nlh;
 	void *hdr;
-	struct team_option_inst *opt_inst;
 	int err;
 	struct sk_buff *skb = NULL;
 	bool incomplete;
 	int i;
 
-	opt_inst = list_first_entry(sel_opt_inst_list,
-				    struct team_option_inst, tmp_list);
+	tmp = list_first_entry(sel_opt_inst_list,
+			       struct team_option_inst, tmp_list);
 
 start_again:
 	err = __send_and_alloc_skb(&skb, team, portid, send_func);
@@ -2456,7 +2456,9 @@ static int team_nl_send_options_get(struct team *team, u32 portid, u32 seq,
 		goto nla_put_failure;
 
 	i = 0;
+	opt_inst = list_prepare_entry(tmp, sel_opt_inst_list, tmp_list);
 	incomplete = false;
+	tmp = NULL;
 	list_for_each_entry_from(opt_inst, sel_opt_inst_list, tmp_list) {
 		err = team_nl_fill_one_option_get(skb, team, opt_inst);
 		if (err) {
@@ -2464,6 +2466,7 @@ static int team_nl_send_options_get(struct team *team, u32 portid, u32 seq,
 				if (!i)
 					goto errout;
 				incomplete = true;
+				tmp = opt_inst;
 				break;
 			}
 			goto errout;
@@ -2707,14 +2710,14 @@ static int team_nl_send_port_list_get(struct team *team, u32 portid, u32 seq,
 	struct nlattr *port_list;
 	struct nlmsghdr *nlh;
 	void *hdr;
-	struct team_port *port;
+	struct team_port *port, *tmp = NULL;
 	int err;
 	struct sk_buff *skb = NULL;
 	bool incomplete;
 	int i;
 
-	port = list_first_entry_or_null(&team->port_list,
-					struct team_port, list);
+	tmp = list_first_entry_or_null(&team->port_list,
+				       struct team_port, list);
 
 start_again:
 	err = __send_and_alloc_skb(&skb, team, portid, send_func);
@@ -2744,7 +2747,9 @@ static int team_nl_send_port_list_get(struct team *team, u32 portid, u32 seq,
 		err = team_nl_fill_one_port_get(skb, one_port);
 		if (err)
 			goto errout;
-	} else if (port) {
+	} else {
+		port = list_prepare_entry(tmp, &team->port_list, list);
+		tmp = NULL;
 		list_for_each_entry_from(port, &team->port_list, list) {
 			err = team_nl_fill_one_port_get(skb, port);
 			if (err) {
@@ -2752,6 +2757,7 @@ static int team_nl_send_port_list_get(struct team *team, u32 portid, u32 seq,
 					if (!i)
 						goto errout;
 					incomplete = true;
+					tmp = port;
 					break;
 				}
 				goto errout;
-- 
2.25.1