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net_sched: avoid resetting active qdisc for multiple times

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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>
This commit is contained in:
Cong Wang 2020-05-26 21:35:26 -07:00 committed by David S. Miller
parent f5a7833e83
commit 70f5096533
1 changed files with 23 additions and 14 deletions
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37
net/sched/sch_generic.c
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@ -1128,6 +1128,28 @@ void dev_activate(struct net_device *dev)
}
EXPORT_SYMBOL(dev_activate);
static void qdisc_deactivate(struct Qdisc *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));
set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
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)
@ -1137,21 +1159,8 @@ static void dev_deactivate_queue(struct net_device *dev,
qdisc = rtnl_dereference(dev_queue->qdisc);
if (qdisc) {
bool nolock = qdisc->flags & TCQ_F_NOLOCK;
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);
qdisc_deactivate(qdisc);
rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
qdisc_reset(qdisc);
spin_unlock_bh(qdisc_lock(qdisc));
if (nolock)
spin_unlock_bh(&qdisc->seqlock);
}
}