linux-kernel - Re: [PATCH net 5/6] net/sched: Refactor qdisc

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Message-ID: <58261cfa-7cba-5cc6-92ac-de155a813df7@mojatatu.com>
Date:   Mon, 8 May 2023 11:11:53 -0300
From:   Pedro Tammela <pctammela@...atatu.com>
To:     Peilin Ye <yepeilin.cs@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>
Cc:     Peilin Ye <peilin.ye@...edance.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.r.fastabend@...el.com>,
        Vlad Buslov <vladbu@...lanox.com>,
        Hillf Danton <hdanton@...a.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Cong Wang <cong.wang@...edance.com>
Subject: Re: [PATCH net 5/6] net/sched: Refactor qdisc_graft() for ingress and
 clsact Qdiscs

On 05/05/2023 21:15, Peilin Ye wrote:
> Grafting ingress and clsact Qdiscs does not need a for-loop in
> qdisc_graft().  Refactor it.  No functional changes intended.
> 
> Signed-off-by: Peilin Ye <peilin.ye@...edance.com>

Just a FYI:
If you decide to keep this refactoring, it will need to be back ported
together with the subsequent fix.
I would personally leave it to net-next.

Thanks for chasing this!

Tested-by: Pedro Tammela <pctammela@...atatu.com>

> ---
>   net/sched/sch_api.c | 20 ++++++++++----------
>   1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
> index 49b9c1bbfdd9..f72a581666a2 100644
> --- a/net/sched/sch_api.c
> +++ b/net/sched/sch_api.c
> @@ -1073,12 +1073,12 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
>   
>   	if (parent == NULL) {
>   		unsigned int i, num_q, ingress;
> +		struct netdev_queue *dev_queue;
>   
>   		ingress = 0;
>   		num_q = dev->num_tx_queues;
>   		if ((q && q->flags & TCQ_F_INGRESS) ||
>   		    (new && new->flags & TCQ_F_INGRESS)) {
> -			num_q = 1;
>   			ingress = 1;
>   			if (!dev_ingress_queue(dev)) {
>   				NL_SET_ERR_MSG(extack, "Device does not have an ingress queue");
> @@ -1094,18 +1094,18 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
>   		if (new && new->ops->attach && !ingress)
>   			goto skip;
>   
> -		for (i = 0; i < num_q; i++) {
> -			struct netdev_queue *dev_queue = dev_ingress_queue(dev);
> -
> -			if (!ingress)
> +		if (!ingress) {
> +			for (i = 0; i < num_q; i++) {
>   				dev_queue = netdev_get_tx_queue(dev, i);
> +				old = dev_graft_qdisc(dev_queue, new);
>   
> -			old = dev_graft_qdisc(dev_queue, new);
> -			if (new && i > 0)
> -				qdisc_refcount_inc(new);
> -
> -			if (!ingress)
> +				if (new && i > 0)
> +					qdisc_refcount_inc(new);
>   				qdisc_put(old);
> +			}
> +		} else {
> +			dev_queue = dev_ingress_queue(dev);
> +			old = dev_graft_qdisc(dev_queue, new);
>   		}
>   
>   skip: