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Message-ID: <543206B4.7090504@gmail.com>
Date: Sun, 05 Oct 2014 20:04:20 -0700
From: John Fastabend <john.fastabend@...il.com>
To: Cong Wang <xiyou.wangcong@...il.com>
CC: netdev@...r.kernel.org, Jamal Hadi Salim <jhs@...atatu.com>,
John Fastabend <john.r.fastabend@...el.com>,
"David S. Miller" <davem@...emloft.net>
Subject: Re: [Patch net-next] net_sched: refactor out tcf_exts
On 10/05/2014 06:47 PM, John Fastabend wrote:
> On 10/03/2014 03:51 PM, Cong Wang wrote:
>> As Jamal pointed it out, tcf_exts is really unnecessary,
>> we can definitely refactor it out without losing any functionality.
>> This could also remove an indirect layer which makes the code
>> much easier to read.
>>
>> This patch:
>>
>> 1) moves exts->action and exts->police into tp->ops, since they
>> are statically assigned
>>
>> 2) moves exts->actions list head out
>>
>> 3) removes exts->type, act->type does the same thing
>>
>> 4) renames tcf_exts_*() functions to tcf_act_*()
>>
>> Cc: Jamal Hadi Salim <jhs@...atatu.com>
>> Cc: John Fastabend <john.r.fastabend@...el.com>
>> Cc: "David S. Miller" <davem@...emloft.net>
>> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
>> ---
>
> Looks OK to me and removes a layer of abstraction without changing
> the code much. This is going to conflict with my series so I'll hold
> off resubmitting it until this is dealt with. I need to respin that
> ematch fix up to drop the ingress lock.
>
> Acked-by: John Fastabend <john.r.fastabend@...el.com>
>
> [...]
>
But after running my test kit I see a null pointer dereference
in cls_cgroup in tcf_act_change().
Looks like you dropped an initializer...
@@ -116,7 +116,6 @@ static int cls_cgroup_change(struct net *net, struct
sk_buff *in_skb,
if (!new)
return -ENOBUFS;
- tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
if (head)
new->handle = head->handle;
else
>>
>> -void tcf_exts_change(struct tcf_proto *tp, struct tcf_exts *dst,
>> - struct tcf_exts *src)
>> +void tcf_act_change(struct tcf_proto *tp, struct list_head *dst,
>> + struct list_head *src)
>> {
>> #ifdef CONFIG_NET_CLS_ACT
>> LIST_HEAD(tmp);
>> tcf_tree_lock(tp);
>> - list_splice_init(&dst->actions, &tmp);
>> - list_splice(&src->actions, &dst->actions);
>> + list_splice_init(dst, &tmp);
>> + list_splice(src, dst);
>> tcf_tree_unlock(tp);
>> tcf_action_destroy(&tmp, TCA_ACT_UNBIND);
>
>
> This is overly complex now that tcf_act_change only
> occurs on null lists. And unattached ones because of the
> RCU semantics so I'm fairly sure we can drop the lock and
> double splice.
>
>
> [...]
>
--
John Fastabend Intel Corporation
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