netdev - Re: [Patch net-next v2 2/4] net_sched: update hierarchical backlog too

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1446233450.6254.29.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Fri, 30 Oct 2015 12:30:50 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Cong Wang <xiyou.wangcong@...il.com>
Cc:	netdev@...r.kernel.org, Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [Patch net-next v2 2/4] net_sched: update hierarchical backlog
 too

On Fri, 2015-10-30 at 11:22 -0700, Cong Wang wrote:
> When the bottom qdisc decides to, for example, drop some packet,
> it calls qdisc_tree_decrease_qlen() to update the queue length
> for all its ancestors, we need to update the backlog too to
> keep the stats on root qdisc accurate.
> 
> Cc: Jamal Hadi Salim <jhs@...atatu.com>
> Acked-by: Jamal Hadi Salim <jhs@...atatu.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>

...

>  
> diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
> index 3abab53..498f0a2 100644
> --- a/net/sched/sch_sfq.c
> +++ b/net/sched/sch_sfq.c
> @@ -346,7 +346,7 @@ static int
>  sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
>  {
>  	struct sfq_sched_data *q = qdisc_priv(sch);
> -	unsigned int hash;
> +	unsigned int hash, dropped;
>  	sfq_index x, qlen;
>  	struct sfq_slot *slot;
>  	int uninitialized_var(ret);
> @@ -461,7 +461,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
>  		return NET_XMIT_SUCCESS;
>  
>  	qlen = slot->qlen;
> -	sfq_drop(sch);
> +	dropped = sfq_drop(sch);
>  	/* Return Congestion Notification only if we dropped a packet
>  	 * from this flow.
>  	 */
> @@ -469,7 +469,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
>  		return NET_XMIT_CN;


I believe you missed the NET_XMIT_CN cases.

SFQ can drop a prior packet, and queue current packet.

qdisc_tree_reduce_backlog() wont be called to update parents.

Not sure about other qdisc(s)


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html