netdev - [PATCH net-next] net: sched: ingress: set 'unlocked' flag for Qdisc ops

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Message-Id: <20190612071435.7367-1-vladbu@mellanox.com>
Date:   Wed, 12 Jun 2019 10:14:35 +0300
From:   Vlad Buslov <vladbu@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        davem@...emloft.net, Vlad Buslov <vladbu@...lanox.com>
Subject: [PATCH net-next] net: sched: ingress: set 'unlocked' flag for Qdisc ops

To remove rtnl lock dependency in tc filter update API when using ingress
Qdisc, set QDISC_CLASS_OPS_DOIT_UNLOCKED flag in ingress Qdisc_class_ops.

Ingress Qdisc ops don't require any modifications to be used without rtnl
lock on tc filter update path. Ingress implementation never changes its
q->block and only releases it when Qdisc is being destroyed. This means it
is enough for RTM_{NEWTFILTER|DELTFILTER|GETTFILTER} message handlers to
hold ingress Qdisc reference while using it without relying on rtnl lock
protection. Unlocked Qdisc ops support is already implemented in filter
update path by unlocked cls API patch set.

Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
---
 net/sched/sch_ingress.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sched/sch_ingress.c b/net/sched/sch_ingress.c
index 0f65f617756b..d5382554e281 100644
--- a/net/sched/sch_ingress.c
+++ b/net/sched/sch_ingress.c
@@ -114,6 +114,7 @@ static int ingress_dump(struct Qdisc *sch, struct sk_buff *skb)
 }

 static const struct Qdisc_class_ops ingress_class_ops = {
+	.flags		=	QDISC_CLASS_OPS_DOIT_UNLOCKED,
 	.leaf		=	ingress_leaf,
 	.find		=	ingress_find,
 	.walk		=	ingress_walk,
-- 
2.21.0