netdev - Re: [Patch net] net_sched: move tcf_lock down after gen_replace

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Message-Id: <20170614.144119.741403806288454976.davem@davemloft.net>
Date:   Wed, 14 Jun 2017 14:41:19 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     xiyou.wangcong@...il.com
Cc:     netdev@...r.kernel.org, nicholashuber@...il.com,
        labbott@...hat.com, jhs@...atatu.com
Subject: Re: [Patch net] net_sched: move tcf_lock down after
 gen_replace_estimator()

From: Cong Wang <xiyou.wangcong@...il.com>
Date: Tue, 13 Jun 2017 13:36:24 -0700

> Laura reported a sleep-in-atomic kernel warning inside
> tcf_act_police_init() which calls gen_replace_estimator() with
> spinlock protection.
> 
> It is not necessary in this case, we already have RTNL lock here
> so it is enough to protect concurrent writers. For the reader,
> i.e. tcf_act_police(), it needs to make decision based on this
> rate estimator, in the worst case we drop more/less packets than
> necessary while changing the rate in parallel, it is still acceptable.
> 
> Reported-by: Laura Abbott <labbott@...hat.com>
> Reported-by: Nick Huber <nicholashuber@...il.com>
> Cc: Jamal Hadi Salim <jhs@...atatu.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>

Applied, thanks.