netdev - Re: [patch net v2 1/4] net/sched: Change tc_action refcnt and bindcnt to atomic

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Message-ID: <CAM_iQpWbfjCH0EFb8RYnOuZQtVtg-Mw-Kzv3GWq81qTVErN6hA@mail.gmail.com>
Date:   Tue, 17 Oct 2017 08:52:54 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Chris Mi <chrism@...lanox.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Lucas Bates <lucasb@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        David Miller <davem@...emloft.net>
Subject: Re: [patch net v2 1/4] net/sched: Change tc_action refcnt and bindcnt
 to atomic

On Mon, Oct 16, 2017 at 6:14 PM, Chris Mi <chrism@...lanox.com> wrote:
> I don't think this bug were introduced by above two commits only.
> Actually, this bug were introduced by several commits, at least the following:
> 1. refcnt and bindcnt are not atomic

Nope, it is perfectly okay with non-atomic as long as no parallel,
and without RCU callback they are perfectly serialized by RTNL.


> 2. passing actions using list instead of arrays (I think initially we are using arrays)

We are discussing patch 1/4, this is patch 2/4, so irrelevant.


> 3. using RCU callbacks

This introduces problem 1.


> So instead of blaming the latest commit, it is better to say it is a pre-git error.

You are wrong.