From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [Patch net] net_sched: fix a missing rcu barrier in
 mini_qdisc_pair_swap()
Date: Tue, 26 Dec 2017 12:30:21 -0500 (EST)
Message-ID: <20171226.123021.1477766854322698861.davem@davemloft.net>
References: <20171221072624.6204-1-xiyou.wangcong@gmail.com>
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Cc: netdev@vger.kernel.org, jiri@mellanox.com, john.fastabend@gmail.com
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From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Wed, 20 Dec 2017 23:26:24 -0800

> The rcu_barrier_bh() in mini_qdisc_pair_swap() is to wait for
> flying RCU callback installed by a previous mini_qdisc_pair_swap(),
> however we miss it on the tp_head==NULL path, which leads to that
> the RCU callback still uses miniq_old->rcu after it is freed together
> with qdisc in qdisc_graft(). So just add it on that path too.
> 
> Fixes: 46209401f8f6 ("net: core: introduce mini_Qdisc and eliminate usage of tp->q for clsact fastpath ")
> Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
> Tested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
> Cc: Jiri Pirko <jiri@mellanox.com>
> Cc: John Fastabend <john.fastabend@gmail.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Applied.