linux-kernel - Re: [PATCH net,v2] net: sched: tbf: don't call qdisc

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Message-ID: <YxY8ToCVWFSV6VqQ@pop-os.localdomain>
Date:   Mon, 5 Sep 2022 11:13:34 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Zhengchao Shao <shaozhengchao@...wei.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, jhs@...atatu.com, jiri@...nulli.us,
        vladbu@...lanox.com, weiyongjun1@...wei.com, yuehaibing@...wei.com
Subject: Re: [PATCH net,v2] net: sched: tbf: don't call qdisc_put() while
 holding tree lock

On Fri, Aug 26, 2022 at 09:39:30AM +0800, Zhengchao Shao wrote:
> The issue is the same to commit c2999f7fb05b ("net: sched: multiq: don't
> call qdisc_put() while holding tree lock"). Qdiscs call qdisc_put() while
> holding sch tree spinlock, which results sleeping-while-atomic BUG.
> 

Hm, did you see an actual warning here??

The commit you mentioned above is a classful Qdisc which accepts
user-specified child Qdisc, but TBF technically does not, I don't think
you can change its default fifo.

Thanks.