From: Wang Hai wanghai38@huawei.com
[ Upstream commit f612466ebecb12a00d9152344ddda6f6345f04dc ]
In attach_default_qdiscs(), if a dev has multiple queues and queue 0 fails to attach qdisc because there is no memory in attach_one_default_qdisc(). Then dev->qdisc will be noop_qdisc by default. But the other queues may be able to successfully attach to default qdisc.
In this case, the fallback to noqueue process will be triggered. If the original attached qdisc is not released and a new one is directly attached, this will cause netdevice reference leaks.
The following is the bug log:
veth0: default qdisc (fq_codel) fail, fallback to noqueue unregister_netdevice: waiting for veth0 to become free. Usage count = 32 leaked reference. qdisc_alloc+0x12e/0x210 qdisc_create_dflt+0x62/0x140 attach_one_default_qdisc.constprop.41+0x44/0x70 dev_activate+0x128/0x290 __dev_open+0x12a/0x190 __dev_change_flags+0x1a2/0x1f0 dev_change_flags+0x23/0x60 do_setlink+0x332/0x1150 __rtnl_newlink+0x52f/0x8e0 rtnl_newlink+0x43/0x70 rtnetlink_rcv_msg+0x140/0x3b0 netlink_rcv_skb+0x50/0x100 netlink_unicast+0x1bb/0x290 netlink_sendmsg+0x37c/0x4e0 sock_sendmsg+0x5f/0x70 ____sys_sendmsg+0x208/0x280
Fix this bug by clearing any non-noop qdiscs that may have been assigned before trying to re-attach.
Fixes: bf6dba76d278 ("net: sched: fallback to qdisc noqueue if default qdisc setup fail") Signed-off-by: Wang Hai wanghai38@huawei.com Link: https://lore.kernel.org/r/20220826090055.24424-1-wanghai38@huawei.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sched/sch_generic.c | 31 ++++++++++++++++--------------- 1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 250d87d993cb7..02299785209c1 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -1083,6 +1083,21 @@ struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue, } EXPORT_SYMBOL(dev_graft_qdisc);
+static void shutdown_scheduler_queue(struct net_device *dev, + struct netdev_queue *dev_queue, + void *_qdisc_default) +{ + struct Qdisc *qdisc = dev_queue->qdisc_sleeping; + struct Qdisc *qdisc_default = _qdisc_default; + + if (qdisc) { + rcu_assign_pointer(dev_queue->qdisc, qdisc_default); + dev_queue->qdisc_sleeping = qdisc_default; + + qdisc_put(qdisc); + } +} + static void attach_one_default_qdisc(struct net_device *dev, struct netdev_queue *dev_queue, void *_unused) @@ -1130,6 +1145,7 @@ static void attach_default_qdiscs(struct net_device *dev) if (qdisc == &noop_qdisc) { netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n", default_qdisc_ops->id, noqueue_qdisc_ops.id); + netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc); dev->priv_flags |= IFF_NO_QUEUE; netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL); qdisc = txq->qdisc_sleeping; @@ -1384,21 +1400,6 @@ void dev_init_scheduler(struct net_device *dev) timer_setup(&dev->watchdog_timer, dev_watchdog, 0); }
-static void shutdown_scheduler_queue(struct net_device *dev, - struct netdev_queue *dev_queue, - void *_qdisc_default) -{ - struct Qdisc *qdisc = dev_queue->qdisc_sleeping; - struct Qdisc *qdisc_default = _qdisc_default; - - if (qdisc) { - rcu_assign_pointer(dev_queue->qdisc, qdisc_default); - dev_queue->qdisc_sleeping = qdisc_default; - - qdisc_put(qdisc); - } -} - void dev_shutdown(struct net_device *dev) { netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);