net_sched: avoid resetting active qdisc for multiple times (70f50965) · Commits · 戴 / test

Except for sch_mq and sch_mqprio, each dev queue points to the same root qdisc, so when we reset the dev queues with netdev_for_each_tx_queue() we end up resetting the same instance of the root qdisc for multiple times. Avoid this by checking the __QDISC_STATE_DEACTIVATED bit in each iteration, so for sch_mq/sch_mqprio, we still reset all of them like before, for the rest, we only reset it once. Reported-by:

Václav Zindulka <vaclav.zindulka@tlapnet.cz> Tested-by:

Václav Zindulka <vaclav.zindulka@tlapnet.cz> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by:

Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/sched/sch_generic.c

+23 −14

Original line number	Diff line number	Diff line
		@@ -1128,31 +1128,40 @@ void dev_activate(struct net_device *dev)
		}
		EXPORT_SYMBOL(dev_activate);

		static void dev_deactivate_queue(struct net_device *dev,
		struct netdev_queue *dev_queue,
		void *_qdisc_default)
		static void qdisc_deactivate(struct Qdisc *qdisc)
		{
		struct Qdisc *qdisc_default = _qdisc_default;
		struct Qdisc *qdisc;

		qdisc = rtnl_dereference(dev_queue->qdisc);
		if (qdisc) {
		bool nolock = qdisc->flags & TCQ_F_NOLOCK;

		if (qdisc->flags & TCQ_F_BUILTIN)
		return;
		if (test_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state))
		return;

		if (nolock)
		spin_lock_bh(&qdisc->seqlock);
		spin_lock_bh(qdisc_lock(qdisc));

		if (!(qdisc->flags & TCQ_F_BUILTIN))
		set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);

		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
		qdisc_reset(qdisc);

		spin_unlock_bh(qdisc_lock(qdisc));
		if (nolock)
		spin_unlock_bh(&qdisc->seqlock);
		}

		static void dev_deactivate_queue(struct net_device *dev,
		struct netdev_queue *dev_queue,
		void *_qdisc_default)
		{
		struct Qdisc *qdisc_default = _qdisc_default;
		struct Qdisc *qdisc;

		qdisc = rtnl_dereference(dev_queue->qdisc);
		if (qdisc) {
		qdisc_deactivate(qdisc);
		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
		}
		}

		static bool some_qdisc_is_busy(struct net_device *dev)

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