linux-kernel - [PATCH net-next] net/sched: taprio: simplify list iteration in taprio_dev

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Date:   Fri, 23 Sep 2022 17:59:21 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org
Cc:     Vinicius Costa Gomes <vinicius.gomes@...el.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH net-next] net/sched: taprio: simplify list iteration in taprio_dev_notifier()

taprio_dev_notifier() subscribes to netdev state changes in order to
determine whether interfaces which have a taprio root qdisc have changed
their link speed, so the internal calculations can be adapted properly.

The 'qdev' temporary variable serves no purpose, because we just use it
only once, and can just as well use qdisc_dev(q->root) directly (or the
"dev" that comes from the netdev notifier; this is because qdev is only
interesting if it was the subject of the state change, _and_ its root
qdisc belongs in the taprio list).

The 'found' variable also doesn't really serve too much of a purpose
either; we can just call taprio_set_picos_per_byte() within the loop,
and exit immediately afterwards.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/sched/sch_taprio.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 136ae21ebce9..0bc6d90e1e51 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1072,9 +1072,7 @@ static int taprio_dev_notifier(struct notifier_block *nb, unsigned long event,
 			       void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
-	struct net_device *qdev;
 	struct taprio_sched *q;
-	bool found = false;

 	ASSERT_RTNL();

@@ -1082,15 +1080,12 @@ static int taprio_dev_notifier(struct notifier_block *nb, unsigned long event,
 		return NOTIFY_DONE;

 	list_for_each_entry(q, &taprio_list, taprio_list) {
-		qdev = qdisc_dev(q->root);
-		if (qdev == dev) {
-			found = true;
-			break;
-		}
-	}
+		if (dev != qdisc_dev(q->root))
+			continue;

-	if (found)
 		taprio_set_picos_per_byte(dev, q);
+		break;
+	}

 	return NOTIFY_DONE;
 }
-- 
2.34.1