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Date:   Mon, 16 Nov 2020 07:30:13 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     Florian Westphal <fw@strlen.de>,
        Matthieu Baerts <matthieu.baerts@tessares.net>,
        linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>,
        Aleksandr Nogikh <nogikh@google.com>,
        Willem de Bruijn <willemb@google.com>,
        linux-next@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH net-next v4] net: linux/skbuff.h: combine SKB_EXTENSIONS
 + KCOV handling
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In-Reply-To: <20201116143121.GC22792@breakpoint.cc>
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        <ffe01857-8609-bad7-ae89-acdaff830278@tessares.net>
        <20201116143121.GC22792@breakpoint.cc>
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On Mon, 16 Nov 2020 15:31:21 +0100 Florian Westphal wrote:
> > > @@ -4151,12 +4150,11 @@ enum skb_ext_id {
> > >   #if IS_ENABLED(CONFIG_MPTCP)
> > >   	SKB_EXT_MPTCP,
> > >   #endif
> > > -#if IS_ENABLED(CONFIG_KCOV)
> > >   	SKB_EXT_KCOV_HANDLE,
> > > -#endif  
> > 
> > I don't think we should remove this #ifdef: the number of extensions are
> > currently limited to 8, we might not want to always have KCOV there even if
> > we don't want it. I think adding items in this enum only when needed was the
> > intension of Florian (+cc) when creating these SKB extensions.
> > Also, this will increase a tiny bit some structures, see "struct skb_ext()".  
> 
> Yes, I would also prefer to retrain the ifdef.
> 
> Another reason was to make sure that any skb_ext_add(..., MY_EXT) gives
> a compile error if the extension is not enabled.

Oh well, sorry for taking you down the wrong path Randy!