netdev - Re: [PATCH net 01/16] net/sched: prepare TC actions to properly validate the control action

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Message-ID: <276985862f96310313d223bd61b1f49326258225.camel@redhat.com>
Date:   Fri, 01 Mar 2019 18:59:50 +0100
From:   Davide Caratti <dcaratti@...hat.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Vlad Buslov <vladbu@...lanox.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net 01/16] net/sched: prepare TC actions to properly
 validate the control action

hello Cong, thanks for reviewing.

On Wed, 2019-02-27 at 17:28 -0800, Cong Wang wrote:
> On Wed, Feb 27, 2019 at 9:41 AM Davide Caratti <dcaratti@...hat.com> wrote:
> > +int tcf_action_check_ctrlact(int action, struct tcf_proto *tp,
> > +                            struct tcf_chain **handle,
> 
> Please use a better name than 'handle'. 'handle' is usually used
> for a hex numeric ID. Here you just want to save the allocated
> tcf_chain to this address.

ok, understood. I will use 'newchain', like done elsewhere.

> +               *handle = tcf_chain_get_by_act(tp->chain->block, chain_index);
> > +               if (!*handle) {
> > +                       ret = -ENOMEM;
> 
> Is -ENOMEM okay here? I feel like it should be -ENOSPC or whatever
> tcf_chain_get_by_act() says.

tcf_chain_by_act() calls __tcf_chain_get() with 'create' equal to true.

So, if a chain with the given index does not exist, tcf_chain_create()
will try to create it - and there, the only possible failure I see is
kzalloc().

That's why I think -ENOMEM is ok, at least for the current net/sched code.

--
davide