From: Yunsheng Lin <linyunsheng@huawei.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>,
Jiri Pirko <jiri@resnulli.us>,
"David Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
"Linux Kernel Network Developers" <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, <linuxarm@huawei.com>
Subject: Re: [PATCH net-next] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc
Date: Wed, 2 Sep 2020 16:14:48 +0800 [thread overview]
Message-ID: <6984825d-1ef7-bf58-75fe-cee1bafe3c1a@huawei.com> (raw)
In-Reply-To: <1f7208e6-8667-e542-88dd-bd80a6c59fd2@gmail.com>
On 2020/9/2 15:32, Eric Dumazet wrote:
>
>
> On 9/1/20 11:34 PM, Yunsheng Lin wrote:
>
>>
>> I am not familiar with TCQ_F_CAN_BYPASS.
>> From my understanding, the problem is that there is no order between
>> qdisc enqueuing and qdisc reset.
>
> Thw qdisc_reset() should be done after rcu grace period, when there is guarantee no enqueue is in progress.
>
> qdisc_destroy() already has a qdisc_reset() call, I am not sure why qdisc_deactivate() is also calling qdisc_reset()
That is a good point.
Do we allow skb left in qdisc when the qdisc is deactivated state?
And qdisc_destroy() is not always called after qdisc_deactivate() is called.
If we allow skb left in qdisc when the qdisc is deactivated state, then it is
huge change of semantics for qdisc_deactivate(), and I am not sure how many
cases will affected by this change.
>
>
>
next prev parent reply other threads:[~2020-09-02 8:15 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 0:55 [PATCH net-next] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc Yunsheng Lin
2020-09-01 6:48 ` Eric Dumazet
2020-09-01 7:27 ` Yunsheng Lin
2020-09-01 18:34 ` David Miller
2020-09-02 1:43 ` Yunsheng Lin
2020-09-01 18:24 ` Cong Wang
2020-09-02 1:42 ` Yunsheng Lin
2020-09-02 4:41 ` Cong Wang
2020-09-02 6:34 ` Yunsheng Lin
2020-09-02 7:32 ` Eric Dumazet
2020-09-02 8:14 ` Yunsheng Lin [this message]
2020-09-02 9:20 ` Eric Dumazet
2020-09-03 1:14 ` Yunsheng Lin
2020-09-03 7:24 ` Eric Dumazet
2020-09-04 8:10 ` Yunsheng Lin
2020-09-03 0:35 ` Cong Wang
2020-09-03 1:21 ` Yunsheng Lin
2020-09-03 1:48 ` Cong Wang
2020-09-03 2:22 ` Yunsheng Lin
2020-09-03 2:53 ` Cong Wang
2020-09-04 1:30 ` John Fastabend
2020-09-04 8:08 ` Yunsheng Lin
2020-09-06 8:52 ` [net] 6fd0d0dede: hwsim.ap_ht40_5ghz_switch.fail kernel test robot
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