netdev - Re: [PATCH net-next 3/3] net/sched: act_pedit: rate limit datapath messages

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Date:   Fri, 10 Mar 2023 15:21:16 +0100
From:   Simon Horman <simon.horman@...igine.com>
To:     Pedro Tammela <pctammela@...atatu.com>
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com
Subject: Re: [PATCH net-next 3/3] net/sched: act_pedit: rate limit datapath
 messages

On Thu, Mar 09, 2023 at 03:51:58PM -0300, Pedro Tammela wrote:
> Unbounded info messages in the pedit datapath can flood the printk ring buffer quite easily
> depending on the action created. As these messages are informational, usually printing
> some, not all, is enough to bring attention to the real issue.

Would this reasoning also apply to other TC actions?

> Reviewed-by: Jamal Hadi Salim <jhs@...atatu.com>
> Signed-off-by: Pedro Tammela <pctammela@...atatu.com>
> ---
>  net/sched/act_pedit.c | 17 +++++++----------
>  1 file changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
> index e42cbfc369ff..b5a8fc19ee55 100644
> --- a/net/sched/act_pedit.c
> +++ b/net/sched/act_pedit.c
> @@ -388,9 +388,8 @@ TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb,
>  		}
>  
>  		rc = pedit_skb_hdr_offset(skb, htype, &hoffset);
> -		if (rc) {
> -			pr_info("tc action pedit bad header type specified (0x%x)\n",
> -				htype);
> +		if (unlikely(rc)) {

Do you really need unlikely() here (and no where else?)

> +			pr_info_ratelimited("tc action pedit bad header type specified (0x%x)\n", htype);
>  			goto bad;
>  		}
>  

...