netdev - Re: [Patch net 1/2] net_sched: defer tcf_idr_insert() in tcf_action_init

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Date:   Fri, 25 Sep 2020 12:22:15 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Vlad Buslov <vlad@...lov.dev>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Vlad Buslov <vladbu@...lanox.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>
Subject: Re: [Patch net 1/2] net_sched: defer tcf_idr_insert() in tcf_action_init_1()

On Fri, Sep 25, 2020 at 8:24 AM Vlad Buslov <vlad@...lov.dev> wrote:
> > +     if (TC_ACT_EXT_CMP(a->tcfa_action, TC_ACT_GOTO_CHAIN) &&
> > +         !rcu_access_pointer(a->goto_chain)) {
> > +             tcf_action_destroy_1(a, bind);
> > +             NL_SET_ERR_MSG(extack, "can't use goto chain with NULL chain");
> > +             return ERR_PTR(-EINVAL);
> > +     }
>
> I don't think calling tcf_action_destoy_1() is enough here. Since you
> moved this block before assigning cookie and releasing the module, you
> also need to release them manually in addition to destroying the action
> instance.
>

tcf_action_destoy_1() eventually calls free_tcf() which frees cookie and
tcf_action_destroy() which releases module refcnt.

What am I missing here?

Thanks.