netdev - Re: [PATCH net] net, sched: respect rcu grace period on cls destruction

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Date:   Mon, 28 Nov 2016 11:51:12 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     paulmck@...ux.vnet.ibm.com
CC:     Cong Wang <xiyou.wangcong@...il.com>,
        David Miller <davem@...emloft.net>,
        John Fastabend <john.fastabend@...il.com>,
        Roi Dayan <roid@...lanox.com>, ast@...com,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Jiri Pirko <jiri@...lanox.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net, sched: respect rcu grace period on cls destruction

On 11/28/2016 11:47 AM, Paul E. McKenney wrote:
> On Mon, Nov 28, 2016 at 10:09:16AM +0100, Daniel Borkmann wrote:
>> On 11/28/2016 07:57 AM, Cong Wang wrote:
[...]
>>> The ugly part is the work struct, I am not an RCU expert so don't know if we
>>> have any API to execute an RCU callback in process context. Paul?
>>
>> Same way we do this in BPF with prog destruction, by the way. I'm not aware
>> of any callback API for RCU that lets you do this, but maybe Paul knows.
>
> RCU callbacks are always executed in softirq context, so yes, you do need
> to use something like a work struct.  (Or a wakeup to a kthread or
> whatever.)

Ok, thanks for the confirmation!

Daniel