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Date:   Wed, 17 May 2023 11:48:05 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Vlad Buslov <vladbu@nvidia.com>
Cc:     Peilin Ye <yepeilin.cs@gmail.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
Message-ID: <20230517114805.29e9bdca@kernel.org>
In-Reply-To: <87ttwbjq6y.fsf@nvidia.com>
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        <20230516122205.6f198c3e@kernel.org>
        <87y1lojbus.fsf@nvidia.com>
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On Wed, 17 May 2023 11:49:10 +0300 Vlad Buslov wrote:
> On Tue 16 May 2023 at 17:39, Jakub Kicinski <kuba@kernel.org> wrote:
> > On Tue, 16 May 2023 15:58:46 -0700 Peilin Ye wrote:  
> >> 
> >> 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.  
> 
> I wonder if somehow leveraging existing tc_modify_qdisc() 'replay'
> functionality instead of returning error to the user would be a better
> approach? Currently the function is replayed when qdisc_create() returns
> EAGAIN. It should be trivial to do the same for qdisc_graft() result.

Sounds better than returning -EBUSY to the user and expecting them 
to retry, yes.