netdev - Re: [PATCH net-next] net: sched: ingress: set 'unlocked' flag for Qdisc ops

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Message-ID: <52082ab2-7db8-b047-f42f-a5c69ba9c303@iogearbox.net>
Date:   Wed, 12 Jun 2019 18:33:13 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Vlad Buslov <vladbu@...lanox.com>, netdev@...r.kernel.org
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        davem@...emloft.net, alexei.starovoitov@...il.com
Subject: Re: [PATCH net-next] net: sched: ingress: set 'unlocked' flag for
 Qdisc ops

On 06/12/2019 09:14 AM, Vlad Buslov wrote:
> To remove rtnl lock dependency in tc filter update API when using ingress
> Qdisc, set QDISC_CLASS_OPS_DOIT_UNLOCKED flag in ingress Qdisc_class_ops.
> 
> Ingress Qdisc ops don't require any modifications to be used without rtnl
> lock on tc filter update path. Ingress implementation never changes its
> q->block and only releases it when Qdisc is being destroyed. This means it
> is enough for RTM_{NEWTFILTER|DELTFILTER|GETTFILTER} message handlers to
> hold ingress Qdisc reference while using it without relying on rtnl lock
> protection. Unlocked Qdisc ops support is already implemented in filter
> update path by unlocked cls API patch set.
> 
> Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
> ---
>  net/sched/sch_ingress.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/sched/sch_ingress.c b/net/sched/sch_ingress.c
> index 0f65f617756b..d5382554e281 100644
> --- a/net/sched/sch_ingress.c
> +++ b/net/sched/sch_ingress.c
> @@ -114,6 +114,7 @@ static int ingress_dump(struct Qdisc *sch, struct sk_buff *skb)
>  }
>  
>  static const struct Qdisc_class_ops ingress_class_ops = {
> +	.flags		=	QDISC_CLASS_OPS_DOIT_UNLOCKED,
>  	.leaf		=	ingress_leaf,
>  	.find		=	ingress_find,
>  	.walk		=	ingress_walk,
> 

Vlad, why is clsact_class_ops not updated here? Please elaborate!