linux-kernel - Re: [PATCH net-next] net: linux/skbuff.h: combine NET + KCOV handling

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Message-ID: <52502fe4-8f41-0630-5b9c-be2e07b6932c@tessares.net>
Date:   Sat, 14 Nov 2020 09:01:54 +0100
From:   Matthieu Baerts <matthieu.baerts@...sares.net>
To:     Randy Dunlap <rdunlap@...radead.org>, linux-kernel@...r.kernel.org
Cc:     kernel test robot <lkp@...el.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>, linux-next@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: linux/skbuff.h: combine NET + KCOV handling

Hi Randy,

On 14/11/2020 02:11, Randy Dunlap wrote:
> The previous Kconfig patch led to some other build errors as
> reported by the 0day bot and my own overnight build testing.

Thank you for looking at that!

I had the same issue and I was going to propose a similar fix with one 
small difference, please see below.

> --- linux-next-20201113.orig/include/linux/skbuff.h
> +++ linux-next-20201113/include/linux/skbuff.h
> @@ -4608,7 +4608,7 @@ static inline void skb_reset_redirect(st
>   #endif
>   }
>   
> -#ifdef CONFIG_KCOV
> +#if IS_ENABLED(CONFIG_KCOV) && IS_ENABLED(CONFIG_NET)
>   static inline void skb_set_kcov_handle(struct sk_buff *skb,
Should we have here CONFIG_SKB_EXTENSIONS instead of CONFIG_NET?

It is valid to use NET thanks to your commit 85ce50d337d1 ("net: kcov: 
don't select SKB_EXTENSIONS when there is no NET") that links 
SKB_EXTENSIONS with NET for KCOV but it looks strange to me to use a 
"non direct" dependence :)
I mean: here below, skb_ext_add() and skb_ext_find() are called but they 
are defined only if SKB_EXTENSIONS is enabled, not only NET.

But as I said, this patch fixes the issue. It's fine for me if we prefer 
to use CONFIG_NET.

> @@ -4636,7 +4636,7 @@ static inline u64 skb_get_kcov_handle(st
>   static inline void skb_set_kcov_handle(struct sk_buff *skb,
>   				       const u64 kcov_handle) { }
>   static inline u64 skb_get_kcov_handle(struct sk_buff *skb) { return 0; }
> -#endif /* CONFIG_KCOV */
> +#endif /* CONFIG_KCOV &&  CONFIG_NET */

(Small detail if you post a v2: there is an extra space between "&&" and 
"CONFIG_NET")

Cheers,
Matt
-- 
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