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Date: Tue, 16 May 2023 17:39:02 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Peilin Ye <yepeilin.cs@gmail.com>
Cc: Vlad Buslov <vladbu@nvidia.com>, Jiri Pirko <jiri@resnulli.us>, Daniel
 Borkmann <daniel@iogearbox.net>, "David S. Miller" <davem@davemloft.net>,
 Eric Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Jamal
 Hadi Salim <jhs@mojatatu.com>, Cong Wang <xiyou.wangcong@gmail.com>, Peilin
 Ye <peilin.ye@bytedance.com>, John Fastabend <john.fastabend@gmail.com>,
 Pedro Tammela <pctammela@mojatatu.com>, Hillf Danton <hdanton@sina.com>,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Cong Wang
 <cong.wang@bytedance.com>
Subject: Re: [PATCH net 6/6] net/sched: qdisc_destroy() old ingress and
 clsact Qdiscs before grafting
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On Tue, 16 May 2023 15:58:46 -0700 Peilin Ye wrote:
> > Given Peilin's investigation I think fix without changing core may
> > indeed be hard. I'm not sure if returning -EBUSY when qdisc refcnt
> > is elevated will be appreciated by the users, do we already have
> > similar behavior in other parts of TC?  
> 
> Seems like trying to delete an "in-use" cls_u32 filter returns -EBUSY

I meant -EBUSY due to a race (another operation being in flight).
I think that's different.