netdev - Re: [PATCH RFC net-next v2 1/1] net: sched: Disambiguate verdict from return code

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Message-ID: <20231014190051.GA23755@breakpoint.cc>
Date: Sat, 14 Oct 2023 21:00:51 +0200
From: Florian Westphal <fw@...len.de>
To: Victor Nogueira <victor@...atatu.com>
Cc: jhs@...atatu.com, daniel@...earbox.net, xiyou.wangcong@...il.com,
	jiri@...nulli.us, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, paulb@...dia.com,
	bpf@...r.kernel.org, mleitner@...hat.com, martin.lau@...ux.dev,
	dcaratti@...hat.com, netdev@...r.kernel.org, kernel@...atatu.com
Subject: Re: [PATCH RFC net-next v2 1/1] net: sched: Disambiguate verdict
 from return code

Victor Nogueira <victor@...atatu.com> wrote:
> +	FN(TC_ALLOC_SKB_EXT)		\

I think that SKB_DROP_REASON_NOMEM is fine for this, adding
a new drop reason for every type of object alloction failure
doesn't help.

The other ones are things that do point at tc specific config problems
so no objections there.

>  			ext = tc_skb_ext_alloc(skb);
> -			if (WARN_ON_ONCE(!ext))
> +			if (WARN_ON_ONCE(!ext)) {
> +				u32 drop_reason = SKB_TC_ALLOC_SKB_EXT;
> +
> +				tcf_set_drop_reason(res, drop_reason);

Unrelated to your patch, but I think this WARN_ON makes no sense.

There is nothing the user or a developer could do about that GFP_ATOMIC failure.

Also I see this patch gets rid of some, but not all, CONFIG_NET_CLS_ACT ifdefs.
The changelog should mention why.

Otherwise this LGTM.