netdev - Re: [PATCH net-next 09/12] net: sched: flower: handle concurrent tcf proto deletion

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Message-ID: <CAM_iQpWdKR1JJsqarzLSuzaUDfPeTzPZMjCUb-ENj8aG62v_nA@mail.gmail.com>
Date:   Mon, 18 Feb 2019 12:47:56 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Vlad Buslov <vladbu@...lanox.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH net-next 09/12] net: sched: flower: handle concurrent tcf
 proto deletion

On Wed, Feb 13, 2019 at 11:47 PM Vlad Buslov <vladbu@...lanox.com> wrote:
>
> Without rtnl lock protection tcf proto can be deleted concurrently. Check
> tcf proto 'deleting' flag after taking tcf spinlock to verify that no
> concurrent deletion is in progress. Return EAGAIN error if concurrent
> deletion detected, which will cause caller to retry and possibly create new
> instance of tcf proto.
>

Please state the reason why you prefer retry over locking the whole
tp without retrying, that is why and how it is better?

Personally I always prefer non-retry logic, because it is very easy
to understand and justify its correctness.

As you prefer otherwise, please share your reasoning in changelog.

Thanks!