From: Florian Westphal <fw@strlen.de>
To: Matthieu Baerts <matthieu.baerts@tessares.net>
Cc: Randy Dunlap <rdunlap@infradead.org>,
linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>,
Aleksandr Nogikh <nogikh@google.com>,
Willem de Bruijn <willemb@google.com>,
Jakub Kicinski <kuba@kernel.org>,
linux-next@vger.kernel.org, netdev@vger.kernel.org,
Florian Westphal <fw@strlen.de>
Subject: Re: [PATCH net-next v4] net: linux/skbuff.h: combine SKB_EXTENSIONS + KCOV handling
Date: Mon, 16 Nov 2020 15:31:21 +0100 [thread overview]
Message-ID: <20201116143121.GC22792@breakpoint.cc> (raw)
In-Reply-To: <ffe01857-8609-bad7-ae89-acdaff830278@tessares.net>
Matthieu Baerts <matthieu.baerts@tessares.net> wrote:
> > --- linux-next-20201113.orig/include/linux/skbuff.h
> > +++ linux-next-20201113/include/linux/skbuff.h
> > @@ -4137,7 +4137,6 @@ static inline void skb_set_nfct(struct s
> > #endif
> > }
> > -#ifdef CONFIG_SKB_EXTENSIONS
> > enum skb_ext_id {
> > #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
> > SKB_EXT_BRIDGE_NF,
> > @@ -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.
> So if we think it is better to remove these #ifdef here, we should be OK.
> But if we prefer not to do that, we should then not add stubs for
> skb_ext_{add,find}() and keep the ones for skb_[gs]et_kcov_handle().
Yes, exactly, I did not add these stubs because I could not figure out
a case where an empty skb_ext_{add,find} would be wanted.
If your code calls skb_ext_add() but no skb extensions exist you forgot
a SELECT/DEPENDS SKB_EXTENSIONS in Kconfig & compiler error would tell
you that.
next prev parent reply other threads:[~2020-11-16 14:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 3:17 [PATCH net-next v4] net: linux/skbuff.h: combine SKB_EXTENSIONS + KCOV handling Randy Dunlap
2020-11-16 13:54 ` Matthieu Baerts
2020-11-16 14:31 ` Florian Westphal [this message]
2020-11-16 15:30 ` Jakub Kicinski
2020-11-16 17:08 ` Randy Dunlap
2020-11-16 17:16 ` Florian Westphal
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