netdev - Re: VXLAN RCU error

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Message-ID: <CAM_iQpWuXzNHNiwjX0V8FrEaPMHsaYX-Tm3QKHJqTxLuKqZ1xA@mail.gmail.com>
Date:   Fri, 24 Feb 2017 11:30:05 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Jakub Kicinski <kubakici@...pl>
Cc:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Pravin B Shelar <pshelar@....org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: VXLAN RCU error

On Thu, Feb 23, 2017 at 12:20 AM, Jakub Kicinski <kubakici@...pl> wrote:
>
> Ugh.  Looks like this may not work even if it makes the splat go away.
> synchronize_net() doesn't seem to wait for the _bh() flavor of RCU, so
> we need to add syncronize_rcu_bh() call before freeing the socket or do
> a normal rcu_read_lock()/unlock() on the fast path.  Any RCU experts
> want to comment? :)

But rcu_read_lock_bh() is enforced by upper layer, __dev_queue_xmit(),
I am afraid you can't change it.

Does changing these kfree() to kfree_rcu() work too since there is no
kfree_rcu_bh()?