Subject: Re: [PATCH net-next-2.6] net_sched: sch_sfq: add backlog info in sfq_dump_class_stats()

From: Jarek Poplawski <[email-masked]>
Date: Thu, 16 Dec 2010 08:16:21 +0000

On 2010-12-15 19:18, Eric Dumazet wrote:
> We currently return for each active SFQ slot the number of packets in
> queue. We can also give number of bytes accounted for these packets.
> 
> tc -s class show dev ifb0
> 
> Before patch :
> 
> class sfq 11:3d9 parent 11: 
>  (dropped 0, overlimits 0 requeues 0) 
>  backlog 0b 3p requeues 0 
>  allot 1266 
> 
> After patch :
> 
> class sfq 11:3e4 parent 11: 
>  (dropped 0, overlimits 0 requeues 0) 
>  backlog 4380b 3p requeues 0 
>  allot 1212 
> 
> 
> Signed-off-by: Eric Dumazet <[email-masked]>
> ---
>  net/sched/sch_sfq.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
> index 3cf478d..cb331de 100644
> --- a/net/sched/sch_sfq.c
> +++ b/net/sched/sch_sfq.c
> @@ -548,8 +548,13 @@ static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
>  {
>  	struct sfq_sched_data *q = qdisc_priv(sch);
>  	sfq_index idx = q->ht[cl-1];
> -	struct gnet_stats_queue qs = { .qlen = q->qs[idx].qlen };
> +	struct sk_buff_head *list = &q->qs[idx];
> +	struct gnet_stats_queue qs = { .qlen = list->qlen };
>  	struct tc_sfq_xstats xstats = { .allot = q->allot[idx] };
> +	struct sk_buff *skb;
> +
> +	skb_queue_walk(list, skb)
> +		qs.backlog += qdisc_pkt_len(skb);

I don't think you can walk this list without the qdisc lock.

Jarek P.