Subject: Re: [PATCH] sfq: add dummy bind/unbind handles

From: Jarek Poplawski <[email-masked]>
Date: Sat, 07 Aug 2010 01:17:07 +0200

Stephen Hemminger wrote, On 07.08.2010 00:23:

> Applying a filter to an SFQ qdisc would cause null dereference
> in tcf_bind_filter because although SFQ is classful it didn't
> have all the necessary equipment.
> 
> Better alternative to changing tcf_bind API is to just fix
> SFQ.  This should go to net-2.6 and stable.
> 

Hmm... FYI, actually I've sent already a similar patch to the
original bug report thread (except .unbind_tcf method which
doesn't matter for fixing this bug, so should be rather
implemented in a separate patch, if needed at all in this
case).

Jarek P.

> 
> Signed-off-by: Stephen Hemminger <[email-masked]>
> 
> --- a/net/sched/sch_sfq.c	2010-08-06 15:07:26.552820159 -0700
> +++ b/net/sched/sch_sfq.c	2010-08-06 15:14:24.458287452 -0700
> @@ -502,6 +502,10 @@ static unsigned long sfq_get(struct Qdis
>  	return 0;
>  }
>  
> +static void sfq_put(struct Qdisc *q, unsigned long cl)
> +{
> +}
> +
>  static struct tcf_proto **sfq_find_tcf(struct Qdisc *sch, unsigned long cl)
>  {
>  	struct sfq_sched_data *q = qdisc_priv(sch);
> @@ -511,6 +515,12 @@ static struct tcf_proto **sfq_find_tcf(s
>  	return &q->filter_list;
>  }
>  
> +static unsigned long sfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
> +				  u32 cl)
> +{
> +	return 0;
> +}
> +
>  static int sfq_dump_class(struct Qdisc *sch, unsigned long cl,
>  			  struct sk_buff *skb, struct tcmsg *tcm)
>  {
> @@ -556,6 +566,8 @@ static void sfq_walk(struct Qdisc *sch, 
>  static const struct Qdisc_class_ops sfq_class_ops = {
>  	.get		=	sfq_get,
>  	.tcf_chain	=	sfq_find_tcf,
> +	.bind_tcf	=	sfq_bind_tcf,
> +	.unbind_tcf	=	sfq_put,
>  	.dump		=	sfq_dump_class,
>  	.dump_stats	=	sfq_dump_class_stats,
>